# Fractions

• Feb 18th 2010, 08:23 AM
CSG18
Fractions
How does

(3√2)/6 - (8√2)/216 = (100√2)/216 ?

Thanks
• Feb 18th 2010, 08:44 AM
e^(i*pi)
Quote:

Originally Posted by CSG18
How does

(3√2)/6 - (8√2)/216 = (100√2)/216 ?

Thanks

The LCD of 6 and 216 is 216.

Multiply the first term by 36/36

$\frac{36}{36} \cdot \frac{3\sqrt{2}}{6} = \frac{108 \sqrt2}{216}$

Now they have the same denominator they can be combined

$\frac{108 \sqrt{2} - 8 \sqrt{2}}{216}$

Factor out $\sqrt{2}$

$\frac{\sqrt{2}(108-8)}{216} = \frac{100\sqrt2}{216}$

This equals the RHS but since both numerator and denominator are multiples of 4 we can cancel it down to $\frac{25 \sqrt{2}}{54}$