Question 901511
<pre>
Set {{{x^2 + dx + 64}}} equal to the square of the 
sum of the square roots of the first and third terms

{{{x^2 + dx + 64=(x+8)^2}}}

{{{x^2+dx+64=(x+8)(x+8)}}}

{{{x^2+dx+64=x^2+16x+64}}}

x²'s and 64s cancel

{{{dx=16x}}}

{{{d=16}}}

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x^2 + dx + 49/4

Set {{{x^2 + dx + 49/4}}} equal to the square of the
sum of the square roots of the first and third terms

{{{x^2 + dx + 49/4=(x+7/2)^2}}}

{{{x^2+dx+49/4=(x+7/2)(x+7/2)}}}

{{{x^2+dx+49/4=x^2+7x+49/4}}}

x²'s and {{{49/4}}}s cancel

{{{dx=7x}}}

{{{d=7}}}

Edwin</pre>