Answer:
Explanation:
m
2
−2m−8
Factor the expression by grouping. First, the expression needs to be rewritten as m
2
+am+bm−8. To find a and b, set up a system to be solved.
a+b=−2
ab=1(−8)=−8
Since ab is negative, a and b have the opposite signs. Since a+b is negative, the negative number has greater absolute value than the positive. List all such integer pairs that give product −8.
1,−8
2,−4
Calculate the sum for each pair.
1−8=−7
2−4=−2
The solution is the pair that gives sum −2.
a=−4
b=2
Rewrite m
2
−2m−8 as (m
2
−4m)+(2m−8).
(m
2
−4m)+(2m−8)
Factor out m in the first and 2 in the second group.
m(m−4)+2(m−4)
Factor out common term m−4 by using distributive property.
(m−4)(m+2)