The sum of the first six terms of an A.P is 72 and second term is seven times the fifth term. find the first term and common difference.​

Answers

Answer 1

Hello,

if A.P means arithmetic progression then

let's say a the first term and r the common difference.

[tex]\left\{\begin{array}{ccc}(a)+(a+r)+(a+2r)+...+(a+5r)&=&72\\a+r&=&7*(a+4r)\end{array}\right.\\\\\\\left\{\begin{array}{ccc}6a+15r&=&72\\6a+27r&=&0\end{array}\right.\\\\\\\left\{\begin{array}{ccc}a&=&\dfrac{-9}{2}*r\\-9r+5r&=&24\end{array}\right.\\\\\\\left\{\begin{array}{ccc}r&=&-6\\a&=&27\end{array}\right.\\\\[/tex]


Related Questions

17
Select the correct answer from each drop-down menu.
Consider this system of equations:
2x+ıy=3
(equation A)
fr-y=6
(equation B)
The expressions that give the value of y are
The solution for the given system is
and

Answers

Answer:

The expressions that give the value of y are A - 3B and (1/3)A - B

The solution is (27/13, -60/13)

Step-by-step explanation:

We can see both equation A and equation B.

Equation A: 2x + (1/4)y = 3

Equation B: (2/3)x - y = 6

To find the value of y, we have to solve both equations A and equation B simultaneously. This is done by multiplying equation B by 3 and subtracting from equation A (A - 3B) to get:

(13/4)y = -15

y = -60/13

you can also get y by dividing equation A by 3 and subtracting equation B (1/3A - B)

Put y = -60/13 in equation A to get x:

2x + (1/4)(-60/13) = 3

2x = 3 + 15/13

2x = 54/13

x = 27/13

The solution is (27/13, -60/13)

The rate (In mg carbon/m3/h) at which photosynthesis takes place for a species of phytoplankton is modeled by the function 110I 12 +1+ 9 where I is the light intensity (measured in thousands of foot-candles). For what light intensity is P a maximum?

Answers

Answer:

P is maximum at I = 2

Step-by-step explanation:

Here is the complete question

The rate (in mg carbon/m³/h) at which photosynthesis takes place for a species of phytoplankton is modeled by the function P = 100I/(I² + I + 4) where I is the light intensity (measured in thousands of foot candles). For what light intensity P is a maximum?

To find the value of I at which P is maximum, we differentiate P with respect to I and equate it to zero.

So, dP/dI =  d[100I/(I² + I + 4)]/dI

= [(I² + I + 4)d(100I)/dI - 100Id(I² + I + 4)/dI]/(I² + I + 4)²

= [(I² + I + 4)100 - 100I(2I + 1)]/(I² + I + 4)²

= [100I² + 100I + 400 - 200I² - 100I]/(I² + I + 4)²

= [-100I² + 400]/(I² + I + 4)²

=  -100[I² - 4]/(I² + I + 4)²

Since dP/dI = 0,  -100[I² - 4]/(I² + I + 4)² = 0 ⇒ I² - 4 = 0 ⇒ I² = 4 ⇒ I = ±√4

I = ±2

Since I cannot be negative, we ignore the minus sign

To determine if this is a maximum point, we differentiate dP/dI. So,

d(dP/dI)/dI = d²P/dI² = d[-100[I² - 4]/(I² + I + 4)²]/dI

= [(I² + I + 4)²d(-100[I² - 4])/dI - (-100[I² - 4])d(I² + I + 4)²/dt]/[(I² + I + 4)²]²

= [(I² + I + 4)²(-200I) + 100[I² - 4]) × (2I + 1) × 2(I² + I + 4)]/(I² + I + 4)⁴

= [-200I(I² + I + 4)² + 200[I² - 4])(2I + 1)(I² + I + 4)]/(I² + I + 4)⁴

= [-200(I² + I + 4)[I(I² + I + 4) - [I² - 4])(2I + 1)]]/(I² + I + 4)⁴

= [-200(I² + I + 4)[I³ + I² + 4I - I² + 4])(2I + 1)]]/(I² + I + 4)⁴

= [-200(I² + I + 4)[I³ + 4I + 8])(2I + 1)]]/(I² + I + 4)⁴

Substituting I = 2 into d²P/dI², we have

= [-200(2² + 2 + 4)[2³ + 4(2) + 8])(2(2) + 1)]]/(2² + 2 + 4)⁴

= [-200(4 + 2 + 4)[8 + 8 + 8])(4 + 1)]]/(4 + 2 + 4)⁴

= [-200(10)[24](5)]]/(10)⁴

= -240000/10⁴

= -24

Since d²P/dI² = -24 < 0 at I = 2,  this shows that it I = 2 is a maximum point.

So, P is maximum at I = 2

Help please
What value of x will ensure that the shelves are parallel?

Answers

i’m pretty sure the answer is 84.

180-96=84

for the to be parallel both the angle must be equal

so 7x - 20 = 3x + 20 - > 4x = 40⁰

x = 10⁰

Which is the graph of the equation y-1=- f (x-3)?

Answers

this will be the graph of your equation. hope it helps

1. Students were surveyed and asked if they play lacrosse and/or football. The results are shown below.




What percent of football players also play lacrosse?

Answers

36%

Step-by-step explanation:

28 + 16 = 44 Football players

Of those, 16 are on the lacrosse team.

16 / 44 × 100 = 36.36% (We round to 36%)

To verify:

44 × 36.36% = 15.84 (Which we can round to 16)

Pardon me if it's wrong

Which is the equation of a line perpendicular to the line with the equation: y = −14x + 7

y = -4x - 7

y = 4x + 2

y = 14x − 12

y = −14x + 3

Answers

The answer is y=14x? 3

what is the measure of 6 ?

Answers

Answer:

54°

Step-by-step explanation:

Here :-

13x + 9 + 5x + 9 = 1801 8x + 18= 180 18x = 162x = 9

Measure of 6 :-

6 = 5x + 9 6 = 5*9 +9 6 = 45 + 9 6 = 54°

Answer:

m<6 = m<2 = 54º

Step-by-step explanation:

13x + 9 + 5x + 9 = 180

18x + 18 = 180

18x = 180 - 18

18x = 162

x = 162 / 18

x = 9

13x + 9

13(9) + 9

126

180 - 126

54

m<6 = m<2 = 54º

Can someone please help me. If you do thanks

Answers

Answer:

(B)

Step-by-step explanation:

Can't explain lol, but that's the answer

Yes the answer is B!

Solve for the questions (both of them) and label you answers for which question

Answers

Jjbbh I don’t under stand

A tether ball is attached to the top of a 15-foot pole. Maddy holds the ball 3 feet off the ground and 4 feet from the pole. How long is the rope that the tether ball is attached to?

Answers

Answer:

15.52 ft

Step-by-step explanation:

the length of the rope can be determined using Pythagoras theorem

The Pythagoras theorem : a² + b² = c²

where a = length

b = base

c =  hypotenuse

√15² + 4²

= √225 + 16

=√ 241

= 15.52 ft

Answer:

the answer is b the square root of 160

Step-by-step explanation:

i did it on the assignment

how do I solve this question (step by step)?

Answers

Answer:

see explanation

Step-by-step explanation:

Angles on the circumference subtended on the same arc are equal

Angle at the centre is twice the angle at the circumference subtended on the same arc.

Then

∠ BAC = ∠ BDC = 29°

∠ BOC = 2 × ∠ BDC = 2 × 29° = 58°

John finds that the sum of two numbers is 24 and their difference is one sixth of the sum. Find the smallest number between the two numbers

Answers

Answer:

The smallest number is 10

Step-by-step explanation:

x+y=24---equation 1

x-y=¹/6×24=>x-y=4---equation 2

Add both equations

2x=28

x=14

put x=14 into equation 1

14+y=24

y=24-14=10

What is the image of the point (8,4) after a rotation of 90° counterclockwise about the origin?

Answers

Answer:  (-4, 8)

=========================================================

Explanation:

The 90 degree counterclockwise rotation rule we use is

[tex](x,y) \to (-y,x)[/tex]

the x and y coordinates swap places, and we change the sign of the first coordinate after the swap.

After using that rotation rule, we would go from (8,4) to (-4, 8) which is the final answer.

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

Extra info (optional section):

Define the following three points

A = (0,0)

B = (8,4)

C = (-4,8)

Use the slope formula to find that AB and AC have slopes of 1/2 and -2 in that order.

Those slopes multiply to -1, since (1/2)*(-2) = -1. This is a property of any two perpendicular lines as long as neither line is vertical and neither is horizontal. So this is sufficient to prove that the lines are perpendicular. This further means that a 90 degree rotation has taken place.

Solve: 4(x + 3) ≤ 44


x ≥ 16


x ≤ 16


x ≤ 8


x ≥ 8

Please help

Answers

Answer:

C

Step-by-step explanation:

[tex]4(x + 3) \leqslant 44 \\ \\ 4x + 12 \leqslant 44 \\ 4x \leqslant 44 - 12 \\ 4x \leqslant 32 \\ 4x \div 4 \leqslant 32 \div 4 \\ x \leqslant 8[/tex]


A student answered 68 questions correctly in a test and received a grade
of 85%. How many problems were on the test, if all the problems carried
the same number of points?

Answers

Answer:

There are 80 questions on the test

Step-by-step explanation:

I think this is right, but don't quote me on this.

Find the greatest common factor of the
following monomials:
12a^2, 32a^3

Answers

Answer:

4a^2

Step-by-step explanation:

GCF of 12 and 32 is 4.

GCF of a^3 and a^2 is a^2.

Therefore, the answer is 4a^2.

What is the range of the given function ?
{(-2,0),(-4,-3),(2,-9),(0,5),(-5,7)}

Answers

Answer:

{0,-3,-9,5,7}

Step-by-step explanation:

range = all y values

function =(x,y)

so all the second values are ranges

After simplification, the value of 1-2/1(1+2)-3/(1+2)(1+2+3)-4/(1+2+3)(1+2+3+4)-...-100/(1+2+...+99)(1+2+...+100)
is a proper fraction in its lowest form. Find the difference of its numerator and denominator.

Answers

Answer:  no

Step-by-step explanationn.  .......................................................w:eorkeok,feoferkeorkoe

the question is on the image​

Answers

Answer:

(i) - rectangular prism

(Ii) - triangular prism

(iii) - square pyramid

Step-by-step explanation:

Solve. Algebra 1
1-4p-2p=1-5p

Answers

Answer:

p = 0

Step-by-step explanation:

1 - 4p - 2p = 1 - 5p

-6p + 1 = -5p + 1

-p + 1 = 1

-p = 0

p = 0

is my answers correct?

Answers

Answer:

Saleh is x years old. And 10 years ago he was 100 years old.

Suha is x years old. Saleh is 10 years younger than Suha. Saleh is 100 years old.

Yes it is the correct answer

Evaluate the expression. 24.32

Answers

2^4×3^2 = 144

___________

Answer:

144 would be the answer.

Step-by-step explanation:

Question:- [tex]2^{4}[/tex] · [tex]3^{2}[/tex]

[tex]2^{4}[/tex] = 2 x 2 x 2 x 2

   = 4 x 2 x 2

   = 8 x 2

   = 16

[tex]3^{2}[/tex] = 3 x 3

   = 9

So, [tex]2^{4}[/tex] · [tex]3^{2}[/tex] = 16 x 19

              = 144

please help it’s easy i’ll give u brainilest <33

Answers

Answer:

for (a)

Step-by-step explanation:

15 and 25 are the numbers that come in A union to B

Which ordered pair is the best estimate
for the solution of the system of
equations?

y= 3/2x +6
y=1/4x -2

Answers

Answer: -6.4, -3.6

Explanation: A souloution of the system of equations is, when two equations intercept (y= 3/2x +6, y=1/4x -2)

The scale on a map is 1cm = 250 km. What would be the distance on the map, if the actual distance between the two cities is 1,000km? *​

Answers

Answer:

so if its actually 1000 and that map thing is 250

250 goes into 1000 4 times so

4cm

Hope This Helps!!!

determine if 5yx - 17xy are like terms​

Answers

Step-by-step explanation:

yes they are because they have the same variables which are X& Y

Answer:

5yx-7xy

they are like terms, it's all multiplication just a different arrangement

5xy-7xy=-2xy

Step-by-step explanation:

hope this is helpful

What number could replace the box so that the system of equations has
infinitely many solutions?

A. -9

B. 3

C. 9

D. -3

Answers

Answer:

d  || if its wrong cancel me lol <3

Step-by-step explanation:

Write an equation that represents the line.

Answers

Answer:

y = 7/5x + 7

Step-by-step explanation:

2. What is the area of the figure below. Simplify.

Answers

Answer:

x^2 - 9

Step-by-step explanation:

length = 2x - 6 = 2(x-3)

Area = [2(x-3) * (x + 3)]/2 = (x-3)(x+3) = x^2-9

Answer: x = 9

2x -6= x +3

2x -x= 3 +6

x= 9

Arc AC is adjacent to arc CD. If arc AC measures 35 degrees and arc CD measures 45 degrees, what is the measure of arc AD according to the Arc Addition Postulate?

Answers

Answer:

80°

Step-by-step explanation:

You just need to sum up the values according to arc addition postulate:

the measure of the arc formed by two adjacent arcs is the sum of the measures of the two arcsm(arc AD) = m(arc AC) + m(arc CD)m(arc AD) = 35° + 45° = 80°

Now we have to find,

The measure of arc AD according to the Arc Addition Postulate.

AD is the sum of the measures of the other two arcs. Then measure of AD is,

→ AC + CD

→ 35° + 45°

→ 80° (final answer)

Hence, the measure of arc AD is 80°.

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