Find the sum of the geometric sequence -315, -75, when there are seven terms and select the correct answer below

Given geometric sequence = -3,15,-75,375,....

Common ratio = r =

To find the sum of seven terms,

n = number of terms = 7

a = 1st term = -3

r = common ratio = -5

= - 39063

Sum of 7 terms of the geometric sequence = - 39063

the direct variation says that:

then the equation is of the form is given by:

            where k is the constant variation.

from the given table:

consider any value of x and m(x)=y

x = 2 and m(x)=y = 3

substitute these value in [1]; we have;

divide both sides by 2 we get;

⇒

check:

put x = -1 and m(x) = -1.5

substitute in the equation:

-1.5 = -1.5                   true

therefore, the function m(x) represents a direct variation

graph of this function as shown below:

a.

step-by-step explanation:

step 1 distribute 2 to every term in the parentheses

step 2 add 10 on both sides of the equal sign