Greta says that the expression (2xa)+5 is the same as 2x(a+5). Is she correct?  

1 Answer

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steveschoen | College Teacher | (Level 1) Associate Educator

Posted on

Hi, Brooke,

Since "a" is what's called "a variable", it can represent any number you want.  "You have the power".  So, just literally picking anything, let's say a=3.  So, we would have:

(2x3)+5     and     2x(3+5)

Now, we always do what's in parenthesis first.  So, for the left expression, we do 2x3 first.  2x3 = 6.  Then, adding 5, 6+5 = 11.  So, we have:

(2x3)+5 = 11     and     2x(3+5)

We just haven't done the right one yet.  Now, we do that one.  Always parenthesis first.  So, 3+5 = 8.  Then, we multiply that by the 2 at the beginning.  2x(8) = 16.  So, we have:

(2x3)+5 = 11     and     2x(3+5)=16

So, Brooke, since 11 and 16 are different and not the same, then (2xa)+5 and 2x(a+5) can't be the same.

I hope this assist, Brooke.  Good luck.