(x + 2)^2 + (y – 3)^2 = 40
y = -2x + 4

Which could be the x-coordinate of a solution to the system of equations above?

A) √7

B) √35 / 2

C) (6 + 2√34) /5

D) (4 + 2√191) /5

Let’s substitute. Use the second equation to make the first equation all x-values.

(x+2)^2+(-2x+4-3)^2=40\\(x+2)^2+(-2x+1)^2=40\\\left(x^2+4x+4\right)+\left(4x^2-4x+1\right)=40\\5x^2+5=40\\5x^2=35\\x^2=7

Well, not exactly a walk in the park, but it all comes together nicely! A is the answer.

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