SOLUTION: Tutor could you please help me with this problem, my practice worksheet asked me to "perform the indicated operation"???? thank you 3/2b minus 5/3b^3 Also what is the LCD

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Question 86979: Tutor could you please help me with this problem, my practice worksheet asked me to "perform the indicated operation"????
thank you
3/2b minus 5/3b^3
Also what is the LCD for 7over a^2+2a-63*8 over a+9
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
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.