Math question? Completing the square...

"What must be added to each expression to make a perfect square?"

1. x^2 + 4x

If you could include all the working out then that would be awesome... Thank you so so much!! ^^

The complete the square square patter is (a + b)^2 = a^2 + 2ab + b^2

This translates into x^2 + bx + (b/2)^2 = (x + b/2)^2

x^2 + 4x
=> x^2 + 4x + (4/2)^2 - (4/2)^2
=> x^2 + 4x + 4 - 4
=> (x + 2)^2 - 4

(x + 2)² = x² + 4x + 4

Hence, 4 is added to make x² + 4x a perfect square

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