What value should be added to the expression to create a perfect square

Algebra
Tutor: None Selected Time limit: 1 Day

x^2-20x

Mar 10th, 2015

A perfect square should be of the form:

(x + a)^2

So what must a be? Well, since we will multiply out brackets to make:

(x + a)^2

= x^2 + 2ax + a^2

Then we can see that 2a = -20 (from our original expression). So a = -10, therefore a^2 = 100.

So we need to add 100 to the expression :-) 

Mar 10th, 2015

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Mar 10th, 2015
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Mar 10th, 2015
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