Question

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

Answer 1

`-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`