SOLUTION: I don't know how to write out the problem, but I'll try my best so you can understand it. The problem I have is -3 square root of 20 times square root of 15. The answer I came to

Question 73433: I don't know how to write out the problem, but I'll try my best so you can understand it. The problem I have is -3 square root of 20 times square root of 15. The answer I came to was -30 square root of 3. Is this correct?
Found 2 solutions by Cintchr, bucky:
Answer by Cintchr(481) (Show Source): You can put this solution on YOUR website!

Since you are multiplying, you can combine your square roots right away

Break the 20 and the 15 up into Prime factors

Since we are doing square roots, we pull numbers out from under the radical in pairs, but only one stays.

Multiply the co-efficients

You were right!!
Answer by bucky(2189) (Show Source): You can put this solution on YOUR website!
Here's how I understood what you said ... your problem is:
.

.
and you need to simplify it.
.
Congratulations, your answer is correct! You can check your work and see if you did it
like I did.
.
Here's how I did it:
.
Notice that 20 can be factored into 4 times 5 and 15 can be factored into 3 times 5.
.
Substitute these values into the problem statement to get:
.

.
Now, using the rule that :
.

.
Notice that and that . We can make these
substitutions to get:
.

.
Multiplying out the leading constants ((-3)*2*5) = -30 and the answer becomes:
.

.
Good job! Keep up the good work!
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