Question

15-7(sqrt(15))
/
15+7(sqrt(15))

how can I simplify this? I know it comes to:

- (32 - 7(sqrt( 15 ))
/
17

But can someone show their work? I can figure it out if I can see the steps. Please??? :)

Answer 1

The "conjugate" of
\[15+7\sqrt{15}\] is
\[15-7\sqrt{15}\]
Multiplying those two together produces a rational value.

--

Try doing this:
\[\frac{15-7\sqrt{15}}{15+7\sqrt{15}} \cdot \frac{15-7\sqrt{15}}{15-7\sqrt{15}}\]

Don't cross out the opposites (or we would be back where we started!. Just multiply them together:
\[\frac{(15-7\sqrt{15})(15-7\sqrt{15})}{(15+7\sqrt{15})(15-7\sqrt{15})} \]

Answer 2

@student1988... @muntoo just gave you that expert help you wanted.

Answer 3

hey thanks! I did this, but my multiplication was wrong.