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What value of c makes the polynomial below a perfect square?

+1 vote

x^2 + 6x + c?

C=?
asked Feb 9, 2013 in PRE-ALGEBRA by mathgirl Apprentice

2 Answers

+2 votes

 x2 + 6x + c?

This expression it can be written as

(x)2 + 2(x)(3) +32 - 32 + c

Mathematics formulas: (a + b)2 = a2 + 2ab + b2

(x + 3)2+ (c - 9)

Clearly to make the polynomial a perfect square (c - 9) should be zero.

So, c - 9 = 0

Add 9 to each side.

c = 9

Therefore c = 9.

answered Feb 9, 2013 by britally Apprentice
x^2 - 9x +c
0 votes

The expression is x2 + 6x + c.

 

To change the expression into a perfect square trinomial add (half the x coefficient)² to each side of the expression

 Here x coefficient = 6. so, (half the x coefficient)² = (6/2)2= 9.



Now set c equal to 9 and solve (and in this case it is c) :

c = 9.

 

The value of c is 9.

answered Jul 4, 2014 by lilly Expert

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