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Ivanna is solving a quadratic equation. She wants to find value of x by taking the square root of both sides of the equation. Which equation allows her to do this?

a. x^2 + 14x + 49 = 16
b. x^2 – 12x – 36 = 47
c. x^2 + 49x + 14 = 42
d. x^2 + 4x – 21 = 25

Respuesta :

I believe it's A. That's the only one that has a proper square root on both sides.
a. x^2 + 14x + 49 = 16 correct answer
 x^2 + 14x + 49 is a complete square
 x^2 + 14x + 49=(x+7)²
(x+7)²=16
√(x+7)²=+/-√16