# Correct calculation of squares

• Jul 19th 2013, 11:02 AM
uperkurk
Correct calculation of squares
I always get lost with this kinda thing.

Is the correct way to calculate $3a^2 \rightarrow (3\times a)^2$ or $3\times(a^2)$

Sorry to make a thread just for this (Thinking)

Thanks.
• Jul 19th 2013, 11:11 AM
Plato
Re: Correct calculation of squares
Quote:

Originally Posted by uperkurk
Is the correct way to calculate $3a^2 \rightarrow (3\times a)^2$ or $3\times(a^2)$.

Here is a hint: $(3a)^2=9a^2$.
• Jul 19th 2013, 11:33 AM
uperkurk
Re: Correct calculation of squares
Thanks. So if I had $(3b)^3$ it would equal $27b^3$ So you're just cubing the first term.

So if I had something like $(3a)^2\times(2a)^2$ it would be $9a^2\times4a^2 = 36a^4$ ?
• Jul 19th 2013, 02:29 PM
HallsofIvy
Re: Correct calculation of squares
Quote:

Originally Posted by uperkurk
Thanks. So if I had $(3b)^3$ it would equal $27b^3$

Yes!

Quote:

So you're just cubing the first term.
In a sense, you have cubed the three- cubing the "b" is still "indicated"

Quote:

So if I had something like $(3a)^2\times(2a)^2$ it would be $9a^2\times4a^2 = 36a^4$ ?
Yes, the exponent is on the parentheses so everything inside the parentheses is squared. Essentially, it is the old "order of operations", "PEDMAS": "Parentheses, then exponents, then ...." That is, you do the multiplication inside the parentheses, then do whatever is outside the parentheses.