# Homework Help

• Feb 3rd 2009, 03:57 PM
Homework Help
I have attached the problem.. I know the answer is 75.. My question is how do I come to that answer?
• Feb 3rd 2009, 04:17 PM
elliotyang
(5*sqrt3)^2 = 25*3 = 75
• Feb 3rd 2009, 04:20 PM
jnm07
Its basically saying 5 multiplied by the square root of 3 and whatever you get from doing that, square.

Just find the square root of 3, if you can use a calculator, which comes out to approx. 1.732.... and multiply by 5, which comes to like 8.6602.... Then square that number, and you get 75. Done.
• Feb 3rd 2009, 04:41 PM
Quote:

Originally Posted by jnm07
Its basically saying 5 multiplied by the square root of 3 and whatever you get from doing that, square.

Just find the square root of 3, if you can use a calculator, which comes out to approx. 1.732.... and multiply by 5, which comes to like 8.6602.... Then square that number, and you get 75. Done.

ok great! thanks guys.. I have a t1 83 plus calculator.. How do I put in square roots in it?
• Feb 3rd 2009, 05:09 PM
Mathnasium
Please don't use a calculator - the problem certainly doesn't require one.

(5 * sqrt(3) ) ^2.

The exponent applies to both things inside the parentheses - in other words, the problem could be rewritten as 5^2 times (sqrt(3))^2.

5^2 = 25.

sqrt(3) ^ 2 = 3. (Taking the square root and squaring something are inverse operations, and cancel each other out, much like how addition and subtraction or multiplication and division are inverse operations.)

So now you have 25 * 3 = 75.

Another example:

(7 * sqrt(5) )^2 = 7^2 * (sqrt(5))^2 = 49 * 5 = 245.

No calculator required.
• Feb 3rd 2009, 05:09 PM
elliotyang
NOrmally this kind of question need not use calculator to do. It is just simple operation.
(5*sqrt3)^2=5^2*(sqrt3)^2
=25*3
=75

I think you should clear by now.
• Feb 3rd 2009, 05:11 PM
jnm07
"2nd" (the yellow button up top on the left side, or atleast mines yellow) and the "x^2" button, like 5th one down. Make sure you hit '2nd' though, otherwise itll just square it. you want the square root.