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If using the method of completing the square to solve the quadratic equation x^2+8x-4=0 which number would have to be added to "complete the square"?

I need the answer ASAP. Please help. Thank you

Respuesta :

F0rrestT

x^2 + 8x - 4 = 0

(x^2 + 8x + 8/2^2) - 4 - 8/2^2 = 0

(x^2 + 8x + 16) - 4 - 16 = 0

(x^2 + 8x + 16) - 20 = 0

(x + 4)(x + 4) - 20 = 0

The number that is to be added to complete the square is 8/2^2, or 16.