Question

What value for c will make the expression a perfect square trinomial? x2 – 7x + c

Answer 1

I assume the first part of that equation is x^2. -7/2= 3.5 ; 3.5^2=12.25 sooo it should end up as x^2-7x + 12.25. but I might be wrong.

Answer 2

Answer: 12.25

Step-by-step explanation:

 A perfect square trinomial is written as $ax^2+2abx+b^2$ , where

first term $ax$ = square of first term of binomial

second term=2abx=twice the product of both terms of binomial.

and third term 'c'=square of last term of binomial

In the given polynomial , $x^2+7x+c$, a=1

and 2ab = 7

When we put value of a =1, we get

$2(1)b=7\\\Rightarrow\ b=\frac{7}{2}$

Hence, in place of the question mark makes the given polynomial a perfect square trinomial =$b^2=(\frac{7}{2}^2=12.25$