Radicals

[Hockeyman]

Another problem here:

7 divided by SqRt 2 - SqRt 7 multiplied by:

SqRt 2 + SqRt 7 divided by SqRt 2 + SqRt 7

= 7*SqRt 2 + 7*SqRt 7 divided by SqRt 2(SqRt 2 + SqRt 7) - SqRt 7(SqRt 2 + SqRt 7)

= 7*SqRt 2 + 7*SqRt 7 divided by SqRt 4 + SqRt 14 - SqRt 14 - SqRt 49

= 7*SqRt 2 + 7*SqRt 7 divided by -5

* stands for multiplication

Is this correct? My teacher gave us a different answer, but i keep getting this one and I cannot figure out where I went wrong. Thanks for any help in advance.

 

[Denis]

Another problem here:
7 divided by SqRt 2 - SqRt 7 multiplied by:
SqRt 2 + SqRt 7 divided by SqRt 2 + SqRt 7
= 7*SqRt 2 + 7*SqRt 7 divided by SqRt 2(SqRt 2 + SqRt 7) - SqRt 7(SqRt 2 + SqRt 7)
= 7*SqRt 2 + 7*SqRt 7 divided by SqRt 4 + SqRt 14 - SqRt 14 - SqRt 49
= 7*SqRt 2 + 7*SqRt 7 divided by -5
* stands for multiplication
Is this correct? My teacher gave us a different answer, but i keep getting this one and I cannot figure out where I went wrong. Thanks for any help in advance.

Yes, you're correct; perhaps teacher's answer is simply in different format.

In the future, TYPE THESE LIKE THIS:
Simplify: 7 / [sqrt(2) - sqrt(7)]

Multiply by [sqrt(2) + sqrt(7)] / [sqrt(2) + sqrt(7)] :

{7 / [sqrt(2) - sqrt(7)]} * {[sqrt(2) + sqrt(7)] / [sqrt(2) + sqrt(7)] }

= 7[sqrt(2) + sqrt(7)] / {[sqrt(2) - sqrt(7)] * [sqrt(2) + sqrt(7)] }

= 7[sqrt(2) + sqrt(7)] / (-5)

You can check if you're correct by simply doing the calculation:

opening expression: 7 / [sqrt(2) - sqrt(7)] = -5.68395...
ending expression: 7[sqrt(2) + sqrt(7)] / (-5) = -5.68395...

How does your teacher show it? Like this:
-(7/5)[sqrt(2) + sqrt(7)] ? If so, it's same thing...