The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Maths

Why 2(2(x+3)) is not 4(2x+6) but 4(x+3) ?
Original post by Sasha Shasha
Why 2(2(x+3)) is not 4(2x+6) but 4(x+3) ?


Please show your working ...
Reply 2
Avatar for Selly45
Selly45
7
Girl what? Explain more. I’m literally doing binomials right now and just came across this but what are you talking about?
Reply 3
Avatar for davros
davros
16
Original post by Sasha Shasha
Why 2(2(x+3)) is not 4(2x+6) but 4(x+3) ?

a(bc) = (ab)c for any 3 numbers a, b and c. Why do you think the answer would be 4(2x+6) ?
Original post by Muttley79
Please show your working ...

2(2(x+3)) 2(2(x+3))
4(x+3) or 4(2x+6)
4x+12 8x+24 This one, why its wrong if I multiply 2 with terms within the parentheses which is (x+3) , why we only multiply it with the number which is outside the bracket.I'm sorry if my question sounds dumb
Original post by davros
a(bc) = (ab)c for any 3 numbers a, b and c. Why do you think the answer would be 4(2x+6) ?

2(2(x+3)) 2(2(x+3))
4(x+3) & 4(2x+6)
4x+12 8x+24 This one, why its wrong if I multiply 2 with terms within the parentheses which is (x+3) , why we only multiply it with the number which is outside the bracket.I'm sorry if my question sounds dumb
Reply 6
Avatar for awc14
awc14
13
Original post by Sasha Shasha
2(2(x+3)) 2(2(x+3))
4(x+3) or 4(2x+6)
4x+12 8x+24 This one, why its wrong if I multiply 2 with terms within the parentheses which is (x+3) , why we only multiply it with the number which is outside the bracket.I'm sorry if my question sounds dumb

So when you are multiplying an expression like 2x+3, for example:

2(2x+3) = 4x + 6.

This is because you multiply both 2x and 3 by 2.

However, if you are multiplying a different expression, like 2x * a:

2(2x * a) = 4x * a, as you are multiplying the whole thing by 2
Original post by Sasha Shasha
2(2(x+3)) 2(2(x+3))
4(x+3) or 4(2x+6)
4x+12 8x+24 This one, why its wrong if I multiply 2 with terms within the parentheses which is (x+3) , why we only multiply it with the number which is outside the bracket.I'm sorry if my question sounds dumb

You've used the 2 too many times -

2(2(x + 3)) means use the bold 2 on the bracket
2(2x + 6) then the other 2 on the expanded bracket

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you