Question 86979
3/2b minus 5/3b^3
(3/2b) - (5/3b^3)
The least common denominator is 6b^3
Rewrite each fraction with the lcm as its denominator.
= 9b^2/lcd - 10/lcd
Since the denominators are the same you can combine the numerators to get:
= [9b^2-10]/lcd
= [9b^2-10]/6b^3
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Also what is the LCD for 7over a^2+2a-63*8 over a+9
[7/(a^2+2a-63)] * [8/(a+9)]

= [7/(a+9)(a-7)] * [8/(a+9)]

= [7/(a-7)] * [8/1]

= 56/(a-7)

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Cheers,
Stan H.