Question

What value for c will make the expression a perfect square trinomial? X2 – 7x + c

Answer 1

If you are searching for the number that makes the whole expression a perfect square, you need to take b, divide it by 2, then square it, like this:

${(\frac{b}{2})}^{2}$

In this case, b is -7. You would then divide it by 2 to get 3.5, then square it.

${3.5}^{2}$

You can plug this into a calculator to get an exact value, but this is what c is supposed to be to make a perfect square trinomial. 'b' is always the number next to 'X'.