Question 163331
Find a value for k that will make 4x^2 + 6.4x + k a perfect square. I need to describe the procedure that I used.
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We want the coefficient of x^2 to be 1, divide equation by 4, resulting in:
x^2 + 1.6x + {{{k/4}}} 
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To find the 3rd term, divide the coefficient of x by 2 and square it
{{{k/4}}} = {{{(1.6/2)^2}}}
{{{k/4}}} = .64
k = 4*.64
k = 2.56
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The equation: 4x^2 + 6.4x + 2.56 which is (2x + 1.6)^2
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