Use the summation formula to find a partial sum of a series with the following properties
Geometric
a1= -11
a7= -45,056
n= 7
r= -4

-36,047.

Step-by-step explanation:

Sum of n terms =  a1 .( r^n - 1) / (r - 1)

So Sum of 7 terms =  -11 . ((-4)^7 - 1 / (-4-1)

= -11 *  -16,385 / -5

= -36,047.

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

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step-by-step explanation: