Question 550292
complete the trinomial such that it's a perfect square: y=x^2+__x+81
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c = (b/2a)^2 = 81
a = 1
b/2a = 9
b/2 = 9
b = 18
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--> {{{y = x^2 + 18x + 81 = (x+9)^2}}}