Find the value of a3+8b3 if a+b=10 and ab=18
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Answered by
1
Hello friend
Given a + b = 10 and ab = 18
Consider, a3 + 8b3 = a3 + 8b3
= (a + b)3 − 3 × a × b(a + b) [Since, a3 + b3 = (a + b)− 3ab(a + b)]
= (a + b)3 − 3ab(a + b)
= (10)3 − 6 × 18 × 10
= 1000 − 1080 = -80
Hope it helped u
Given a + b = 10 and ab = 18
Consider, a3 + 8b3 = a3 + 8b3
= (a + b)3 − 3 × a × b(a + b) [Since, a3 + b3 = (a + b)− 3ab(a + b)]
= (a + b)3 − 3ab(a + b)
= (10)3 − 6 × 18 × 10
= 1000 − 1080 = -80
Hope it helped u
swapnil756:
plzzz mark it as brainliest plzz
what a good knowledge
ur saying to whom
Swapnil did it incorrectly he told a+b=10 and during calculation did asva+2b=10
As a+2b=10
i have done it correctly'
that is 8b cube so it will be (2b)cube
so i m ryt
:((
Answered by
4
Hello
I think a + 2b = 10 and ab = 18
_____________________________________________________________
we know ,
a³ + b³ = ( a + b ) ³ - 3ab ( a+b )
_____________________________________________________________
here
a³ - (2b) ³ = (a + 2b ) ³ - 6ab ( a + 2b )
= 10³ - 6 x 18 ( 10 )
= 1000 - 1080
= -80
____________________________________________________________
I think a + 2b = 10 and ab = 18
_____________________________________________________________
we know ,
a³ + b³ = ( a + b ) ³ - 3ab ( a+b )
_____________________________________________________________
here
a³ - (2b) ³ = (a + 2b ) ³ - 6ab ( a + 2b )
= 10³ - 6 x 18 ( 10 )
= 1000 - 1080
= -80
____________________________________________________________
Thanks for helping me
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