How do you solve #x^2+9x+20.25=0# by completing the square?

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Answer 1 · 2016-12-18T13:57:11

#x = -9/2 = -4.5#

The left hand side is already a perfect square trinomial:

#(x+9/2)^2 = x^2+9x+81/4 = x^2+9x+20.25#

So the given equation is equivalent to:

#(x+9/2)^2 = 0#

Hence:

#x+9/2 = 0#

Hence:

#x = -9/2#