SOLUTION: What is the value of c so that y=x^2+15x+c is a perfect square trinomial

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Question 959129: What is the value of c so that y=x^2+15x+c is a perfect square trinomial
Found 2 solutions by jim_thompson5910, MathLover1:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
15 is the x coefficient

take half of 15 to get 15/2

Square 15/2 to get (15/2)^2 = 225/4

The value of c is 225/4

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Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

to be a perfect square trinomial should be y=%28x%2Bc%29%5E2
recall the rule: %28x%2Bc%29%5E2=x%5E2%2B2%2A1%2Ac%2Bc%5E2
so, you have y=x%5E2%2B15x%2Bc and 2%2A1%2Ac=2c=15
then the value of c is 15%2F2=7.5
y=%28x%2B7.5%29%5E2+
so, +c+=+7.5