Question

Help?

Multiply 5SqrT(8)*4SqrT(7)

A)16SqrT(10)

B)20SqrT(15)

C)40SqrT(14)

D) 40

Answer 1

What steps have you taken so far?

Answer 2

ive tried multiplying the outers and i got 20 of course, But if i multiply the inside its 56.

Answer 3

Okay, so you have 56 under the radical, what are all the factors for 56? Can you get a square or two out of it?

Answer 4

7.5 is the rounded number i got for the sqrt.

Answer 5

I like to lay it out like this:
56 = 1*2*2*2*7
and then look to see if I can make a square to pull out.

Answer 6

Notice what you have here:\[\sqrt{56}\rightarrow\sqrt{1*2*2*2*7}\rightarrow\sqrt{1*2^{2}*2*7}\rightarrow 2\sqrt{1*2*7}\]

Answer 7

okay.

Answer 8

But does it make sense to you?

Answer 9

it does until we get to the last part. how do you ger the 2 outside the randical

Answer 10

Well you know that you can break the radical up, so couldn't I just as easily have written the middle step as: \[\sqrt{1}*\sqrt{2^{2}}*\sqrt{2}*\sqrt{7}\]

Answer 11

okay.

Answer 12

Does that make sense?

Answer 13

Yes Sir

Answer 14

Excellent. :)

Answer 15

Looks like you have this figured out. :)

Answer 16

But how do i get the answer?

Answer 17

You already have the answer. All we did was simplify the radical portion of your answer. So what do you get when you put the pieces back together?