The sum of 30 terms of series in A.P, whose last term is 98, is 1635. Find the first term and the common difference.​

Answers

Answer 1

Let a(n) denote the n-th term in the sequence. Because the terms are in arithmetic progression, there is a fixed number d that separates consecutive terms, so that starting with a(1) = a, the next few terms are

a(2) = a(1) + d = a + d

a(3) = a(2) + d = a + 2d

a(4) = a(3) + d = a + 3d

and so on, up to

a(n) = a + (n - 1) d

We're given that the 30th term is 98, so

a(30) = a + 29d = 98

The sum of the first 30 terms is 1635, so that

[tex]\displaystyle \sum_{n=1}^{30}a(n) = \sum_{n=1}^{30}(a+(n-1)d) \\\\ 1635 = a\sum_{n=1}^{30}1 + d\sum_{n=1}^{30}(n-1) \\\\ 1635 = 30a + d\sum_{n=0}^{29}n \\\\ 1635 = 30a + d\sum_{n=1}^{29}n \\\\ 1635 = 30a + \frac{d\times29\times30}2[/tex]

so that

30a + 435d = 1635

Solve the equations in boldface for a and d. I'll eliminate a and solve for d first.

-30 (a + 29d) + (30a + 435d) = -30 (98) + 1635

-30a - 870d + 30a + 435d = -2940 + 1635

-435d = -1305

d = 3

Then

a + 29 (3) = 98

a + 87 = 98

a = 11


Related Questions

PLEASE HELP 30 POINTS

Find the value of x in the triangle below.
804
155
55°
o
75
80°
Ο Ο
85

Answers

Answer:

75°

Step-by-step explanation:

First, we need to know that the interior angle sum of a triangle is always 180°.

Now, to find the missing angle aside from x, we need to complete the sum 180-155=25, seeing 155° lies on a straight line. Remembering the interior angle sum of a triangle is always 180°, it is thus clear that 25+80+x=180. If we complete this equation, x=75.

Hope this helps!

If a 750 ml bottle of juice costs £1.90 and a 1 litre bottle of the same juice costs £2.50 then the 750 ml bottle is better value.

Answers

Answer:

The 1 liter bottle is better value

Step-by-step explanation:

Cost of 750 ml = £1.90

Cost of 1 liter = £2.50

1000 ml = 1 liter

Cost per 250 ml

750 ml / 3 = £1.90 / 3

250 ml = £0.6333333333333

Approximately,

£ 0.633

Cost per 250 ml

1 liter / 4 = £2.50 / 4

250 ml = £0.625

The 750 ml bottle is not a better value

The 1 liter bottle is better value

Please need help explanation need it

Answers

Answer:

308 m^3

Step-by-step explanation:

The volume is given by

V = l*w*h  where l is the length , w is the width and h is the height

V = 7*4*11

V = 308 m^3

Question 2 of 10
Which of the following can you determine, when you use deduction and start
from a given set of rules and conditions?
A. None of these
B. What may be true
C. What may be false
D. What must be true
SUBMIT

Answers

D, it’s a process of elimination
D I don’t know for sure but I think it’s d ……………….

Mọi người giúp em với

Answers

Answer:

bka bla bla bla sorry I newbie

Ashish deposite rs 1000 every month is a recurring deposit account for period of 12 months. If the bank pays interest at a certain rate p.A. And ashish gets 12715 as the maturity value of this account at what rate of interest did he pay every month

Answers

Solution :

Given :

Principal amount, P = Rs. 1000

Time period = 12 months

The maturity value = Rs. 12,715

We know that,

[tex]$ SI = \frac{PTR}{100}$[/tex]

[tex]$SI = 1000 \times \frac{n(n+1)}{2 \times 12} \times \frac{R}{100}$[/tex]

[tex]$SI = 1000 \times \frac{12(12+1)}{2 \times 12} \times \frac{R}{100}$[/tex]

SI = 65 R

So we know,

maturity value = principal amount + SI

12715 = 1000 + 65 R

65 R = 12715 - 1000

65 R = 11715

R = 18%        

So the rate is 18%

                           

Answer:

[tex]R=11\%[/tex] p.a.

Step-by-step explanation:

Given:

the principal amount deposited each month, [tex]P=Rs. 1000[/tex]

amount after maturity of one year, [tex]A=Rs. 12715[/tex]

We have the formula as:

[tex]I=\frac{PR}{100}\times\frac{T(T+1)}{2\times 12}[/tex]

where:

R = rate of interest per annum

T = time in months

[tex]A-12P=\frac{PR}{100}\times\frac{T(T+1)}{2\times 12}[/tex]    [since the principal is deposited each month]

[tex]715=\frac{1000\times R}{100}\times \frac{12\times 13}{24}[/tex]

[tex]R=11\%[/tex] p.a.

Doanh nghiệp bán trả góp 1 bất động sản có giá thanh toán là 32.000trđ . Thu điều cả vốn lẫn lãi trong 10 năm với lãi suất trả chậm là 10% / năm . Xác định số vốn phải thu ở năm thứ 6 ?

Answers

Answer:

Step-by-step explanation:

What is the measure of ∠
A. 6°

B. 42°

C. 60°

D. 49°

Answers

Answer:

<XYZ is equal to 49°

Step-by-step explanation:

Set the two expressions equal to each other so 7x+7=5x+19. Subtract 5x from 7x and 7 from 19 which is equal to 2x=12 that means x is 6. then plug 6 into (7x+7) which is equal to 49.

PLEASE HELP !!!!!!!!!!!!!

Answers

Answer:

the 3rd won for sure

Step-by-step explanation:

hope I helped

Answer:

C

Step-by-step explanation:

The coordinates are all in (x, y) form.

X is how left or right

y is how tall.

If you just look for the individual coordinates given, you will see that all of the Coordinates in C are on the graph.

I hope this helps!

99999+999=????????????????????????????

Answers

Answer:

100998 is the answer.

I hope this help u.

Answer:

100998

Step-by-step explanation:

₁ ₁ ₁ ₁ ₁

99999

+   999

100998

you can also think of it as

99999(+1) + 999(-1)

100000+998

100998

Show Workings.
Question is in attached image.​

Answers

Answer:

A.]A chord of a circle of diameter 40 cm subtends an angle of 70° at the centre of the circle.

Solution given;

diameter [d]=40cm

centre angle [C]=70°

(a) Find the perpendicular distance be tween the chord and the centre of the circle.

Answer:

we have

the perpendicular distance be tween the chord and the centre of the circle=[P]let

we have

P=d Sin (C/2)

=40*sin (70/2)

=22.9cm

the perpendicular distance be tween the chord and the centre of the circle is 22.9cm.

(b) Using = 3.142, find the length of the minor arc.

Solution given;

minor arc=[tex]\frac{70}{360}*πd=\frac{7}{36}*3.142*40[/tex]

=24.44cm

the length of the minor arc. is 24.44cm.

B.]In the diagram, XZ is a diameter of the cir cle XYZW, with centre O and radius 15/2 cm.

If XY = 12 cm, find the area of triangle XYZ.

Solution given:

XY=12cm

XO=15/2cm

XZ=2*15/2=15cm

Now

In right angled triangle XOY [inscribed angle on a diameter is 90°]

By using Pythagoras law

h²=p²+b²

XZ²=XY²+YZ²

15²=12²+YZ²

YZ²=15²-12²

YZ=[tex]\sqrt{81}=9cm[/tex]

:.

base=9cm

perpendicular=12cm

Now

Area of triangle XYZ=½*perpendicular*base

=½*12*9=54cm²

the area of triangle XYZ is 54cm².

Answer:

Question 1

a)

d = 40 cm ⇒ r = 20 cm

Let the perpendicular distance is x.

Connecting the center with  the chord we obtain a right triangle with hypotenuse of r and leg x with adjacent angle of 70/2 = 35°.

From the given we get:

x/20 = cos 35°x = 20 cos 35°x = 16.383 cm (rounded)

b)

The minor arc is 70° and r = 20

The length of the arc is:

s = 2πr*70/360° = 2*3.142*20*7/36 = 24.437 cm (rounded)Question 2

Since XZ is diameter, the opposite angle is the right angle, so the triangle XYZ is a right triangle.

r = 15/2 cm ⇒ XZ = d = 2r = 2*15/2 = 15 cm

Find the missing side, using Pythagorean:

[tex]YZ = \sqrt{XZ^2 - XY^2} = \sqrt{15^2-12^2} = \sqrt{81} = 9[/tex]

The area of the triangle:

A = 1/2*XY*YZ = 1/2*12*9 = 54 cm²

Can someone help me with this math homework please!

Answers

Answer:

(-3,-6) and (-3,2)

Step-by-step explanation:

A line with an undefined slope is vertical. In this case it must have x coordinates equal to -3

If m angle PQR = 141", find each measure. ​

Answers

Answer:

x=6

pqs=82

sqr=59

Step-by-step explanation:

13x + 4 + 10x - 1 = 141

23x + 3= 141

23x = 136

x = 136/23 = 6

~~~~~~~~~~~~~~~

pqs = 13x + 4  = 13(6) + 4 = 78+4 = 82

sqr =  10x - 1 = 10(6)-1 = 60 - 1 = 59

Answer:

x = 6

Angle PQS is 82

Angle SQR is 59

Step-by-step explanation:

13x + 4 + 10x - 1 = 141

Group like terms : 23x + 3 = 141

Subtract 3 from both sides to get 23x = 138

Divide both sides by 23 to get x = 6

Angle PQS: Plug 6 into x  for 13x + 4 = 13 (6) + 4 = 82

Angle SQR: Plug 6 into x for 10x - 1 = 10 (6) -1 = 59

Can I know the answer for the above questions

Answers

Answer:

Step-by-step explanation:

Scarlett made a profit of $250.00 with her mobile car wash company

Answers

Not enough information to solve..... Please make your question more clear

what is 8/9 divide 2/3?

Answers

Answer:

4/3

Step-by-step explanation:

8/9 ÷ 2/3

Simplify the complex fraction.

4/3

Step-by-step explanation:

8/9 ÷ 2/3

Simplify

4/3 is the correct answer

What is the recursive formula for this geometric sequence?
-4, -24, -144, -864, ...
= -4
O A.
an =
2n-1 • 30
OB.
la = -4
ar = 2n-16
fa
= -6
C.
= 2n-1 • 30
= -6
O D.
lan
ar = 2n-1.4

Answers

Answer:

a1 = -4

an = an-1 * 6

Step-by-step explanation:

-4, -24, -144, -864, ...

First find the common ratio

Take the second term and divide by the first term

-24/-4 = 6

The common ratio is 6

The recursive formula is

a1 = -4

an = an-1 * 6

I'm not sure how to answer this!!

Answers

Answer:

I think it's a

Step-by-step explanation:

hsjshbwibs hshhsvsu hshsbsbus

Which is the angle of elevation from C to B?

Answers

Answer:

Angle of elevation = ∠4

Step-by-step explanation:

Angle of elevation of a point point from another point is the angle formed between the line joining these points and the horizontal line.

Therefore, angle of elevation of point B from a point C = ∠4

Option with angle 4 will be the answer.

the sum of three consecutive numbers is five times the difference of the middle number and 22. find the numbers.

Answers

Answer:

The numbers you're looking for are 54, 55, and 56.

Step-by-step explanation:

x + (x + 1) + (x + 2) = 5 * (x + 1 - 22)

3x + 3 = 5x - 105

3 = 2x - 105

108 = 2x

x = 54

x + 1 = 55

x + 2 = 56

What conclusion can be derived by comparing the central tendencies of the two data sets?
A: (7, 6, 3, 1, 6, 2, 4, 6, 3, 5;
B: {2, 2, 2, 3, 4, 5, 2, 8, 7, 6}

Answers

A is the correct answer because u should know

Choose ALL of the ordered pairs that are solutions to the equation.
5y = 2x - 7
a) (6, 0)
b) ( 7, 21)
c) (8, 18)
d) ( -3, 4)

Answers

b) ( 7, 21)

Step-by-step explanation:

5(7)=2(21)-7

35=42-7

35=35

Answer:

None of them

Step-by-step explanation:

a: 5*0=2*6-7 False

b: 5*21=2*7-7 False

c: 5*18=2*8-7 False

d: 5*4=2*-3-7 False

Please HELP! ):
The measure of an interior angle of a regular polygon is eight times the measure of one of its exterior angles. How many sides does the polygon have?

Answers

A polygon has 18 sides :)

which one is the correct answer

Answers

Answer:

B.

Step-by-step explanation:

2x - 31 = - 2x - 314x = 0x = 0

Other equations don't have any value of x.

Answer:

[tex]2x-31=-2x-31[/tex]

Because if you see.. The component of x will get canceled in each of the other 3 options.. ( 2x - 2x) which means no solution.. In option B.. 2x + 2x will give 4x..= 31-31 = 0..

-------------------------

Hope it helps...

Have a great day!!

find value of the variable

Answers

Answer:

x=10

Step-by-step explanation:

16/24=(x-2)/12

or, 16/2=x-2

or, 8=x-2

or, x-2=8

or, x=10

Answered by GAUTHMATH

If x=3 ,y=4 than what is the value?

Answers

I am pretty sure it is 91

please help!!!!!!!!!!!

Answers

it should be this y=1/2x+3
I agree with the answer above

help help............​

Answers

Answer:

please send the pic again clearly

Answer:

I hope it will help you

Step-by-step explanation:

please make me brainlest

thank u

Select the correct answer.
What is the value of x in the triangle?

Answers

Answer:

The answer is A. 21

Hope it helps.

Step-by-step explanation:

• • •

in a shipment of 10,000 headlights, 5% are defective. what is the ratio of defective headlights to non-defective headlights

Answers

Answer:

19:1

Step-by-step explanation:

There are 10000 headlights. If 5% are defective, then 500 are defective. Since we took that 500 out, we get 9500 good headlights. The ratio is 9500:500 or 19:1

The ratio of defective headlights to non-defective headlights will be 19:1.

What is the percentage?

The Percentage is defined as representing any number with respect to 100. It is denoted by the sign %. The percentage stands for "out of 100." Imagine any measurement or object being divided into 100 equal bits.

In mathematics, ratios are used to determine the relationship between two numbers it indicates how many times is one number to another number.

There are 10000 headlights. If 5% are defective, then 500 are defective. Since we took that 500 out, we get 9500 good headlights.

The ratio will be calculated as below:-

Ratio = 9500:500

Ratio = 19:1

Therefore, the ratio of defective headlights to non-defective headlights will be 19:1.

To know more about percentages follow

https://brainly.com/question/24304697

#SPJ5

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