x³+y³ = 91, x+y=7 then xy=?
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Answered by
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(x+y) = 7
cube on both sides,
(x+y)^3 = 7^3
by formula,
x^3 +y^3 +3xy(x+y) = 343
put the values which are given,
91+21xy = 343
21xy = 343-91
21xy = 252
xy= 252/21
12 = xy
cube on both sides,
(x+y)^3 = 7^3
by formula,
x^3 +y^3 +3xy(x+y) = 343
put the values which are given,
91+21xy = 343
21xy = 343-91
21xy = 252
xy= 252/21
12 = xy
abhi569:
your welcome nova
Answered by
2
I Hope it will help u
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