The common difference ,d in an arithmetic sequence whose fourth term is 16 and whose seventh therm is 31

d=5

Step-by-step explanation:

Arithmetic progression

An=a1+d(n-1)

An= nth term

A1= first term

D= common difference

N= nth position

We are given the 4th and 7th terms

For 4th term,n=4

A4=a1+d(4-1)

A4= 16

16= a1+d(4-1)

16= a1+3dequation 1

For the 7th term,n=7

A7=a1+d(7-1)

A7= 31

31=a1+6dequation 2

Bring them together

16=a1+3d

31=a1+6d

Subtract equation 1 from 2

So we have

15=3d

D=15/3

D=5

Therefore, the common difference is 5

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

$9.89

step-by-step explanation:

9.90 = p x .06 x .25 (3/12 changed to a decimal)

9.90 = p x 0.015

9.90 - 0.015 = p

9.89 = p