How do you multiply #-5(a-2b) #?

1 Answer
Tony B
Jul 10, 2016

#-5(a-2b) = -5a+10b#

Explanation:

#color(blue)("The teaching bit")#

The purpose of the brackets in this question is to group things.

Let me demonstrate:

Consider #3xx5 =15#

This is #5+5+5 larr" Three lots of 5 all put together"#
'.................................................................
But 5 can be written in many ways. Suppose we write 5 as 4 + 1

The #3xx5 # is exactly the same as #3xx(4+1)#

So we have 3 lots of #(4+1)# giving

#(4+1)+(4+1)+(4+1)#

#4+4+4" "+1+1+1#

Observe that we have 3 lots of everything inside the brackets.
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#color(blue)("Answering you question")#

#-5(a-2b) = -5a+10b#

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