How do you multiply -5a (a-1)?

1 Answer
Alan P.
Jul 1, 2015

-5a(a-1) = -25a^2+5a

Explanation:

In general, the distributive property (of multiplication over subtraction) says:
color(white)("XXXX")m(p-q) =mp -mq

Setting
color(white)("XXXX")m=(-5a)
color(white)("XXXX")p=(5a)
color(white)("XXXX")q= (1)
this gives
color(white)("XXXX")(-5a)(5a) - (-5a)(1)
color(white)("XXXX")=-25a^2 +5a

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