I know how to factor a trinomial into a product of two binomials. I know how to do the foil method. But how do I factor an equation like this!?
(m-5)(m+4)+8
I need to know what something like this simplifies to and how to do it. Please help me!
First expand the bracketed terms to get:
(m-5)(m+4) + 8 → m2 - m - 20 + 8 → m2 - m - 12
Now notice that 12 is the product of 4 and 3, and 1 is the difference between 4 and 3.
Taking the signs into account this gives us: m2 - m - 12 = (m - 4)(m + 3)
I know how to factor a trinomial into a product of two binomials.
I know how to do the foil method.
But how do I factor an equation like this!?
(m-5)(m+4)+8
\(\begin{array}{|rcll|} \hline && \mathbf{(m-5)(m+4)+8} \\ &=& (m-5)(m+4)+4+4 \\ &=& (m-5)(m+4)+4+4 +m-m\\ &=& (m-5)(m+4)+(m+4)-(m-4) \\ &=& (m+4)[(m-5)+1]-(m-4) \\ &=& (m+4)(m-4)-(m-4) \\ &=& (m-4)[(m+4)-1] \\ &\mathbf{=}& \mathbf{(m-4)(m+3)} \\ \hline \end{array}\)