Question

I know the answer is 4 I just don't know how they got it.

Answer 1

\[\sqrt{16-2b}=\sqrt{2b}\]

Answer 2

Wouldn't the -2b end up canceling the positive 2b and then you'd just be left with the square root of 16 which is 4?

Answer 3

No, remember that signs change when switching sides of the equation.

\[\sqrt{16-2b} = \sqrt{2b}\]
\[\sqrt{16} - \sqrt{2b}\ = \sqrt{2b}\]
\[\sqrt{16} = \sqrt{2b}\ +\sqrt{2b}\]
\[\sqrt{16} = \sqrt{2b+2b}\]
\[\sqrt{16} = \sqrt{4b}\]
or b=4

Answer 4

Thanks!(: