SOLUTION: Fill in the blank to make the trinomial a perfect square trinomial: (___)z^2 -20z+4

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Question 951949: Fill in the blank to make the trinomial a perfect square trinomial:
(___)z^2 -20z+4
Answer by amarjeeth123(569) About Me  (Show Source):
You can put this solution on YOUR website!
We have (a-b)^2=a^2-2ab+b^2
Comparing (___)z^2 -20z+4 we get
2ab=-20z..............equation 1
and b^2=4
b=2...................equation 2
Substituting 2 in 1 we get,
4a=-20z
a=-5z
a^2=25z^2
The answer is 25.