Ifa+b=10 and ab=21 find the value of a cube b cube
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Answered by
3
(a+b) whole cube =a cube + b cube +3ab(a+b)
a+b=10, ab=21 then
(10)whole cube=a cube + b cube +3×21(10)
1000=a cube + b cube +63×10
1000-630=a cube + b cube
370=a cube + b cube
a+b=10, ab=21 then
(10)whole cube=a cube + b cube +3×21(10)
1000=a cube + b cube +63×10
1000-630=a cube + b cube
370=a cube + b cube
Answered by
3
Hey !
a + b = 10
ab = 21
To find :-
a³ + b³
a³ + b³ = [ a+ b] ³ - 3ab [a+b]
= 10³ - 3 × 21 [ 10 ]
= 1000 - 63 × 10
= 370
Hence ,
a³ + b³ = 370
a + b = 10
ab = 21
To find :-
a³ + b³
a³ + b³ = [ a+ b] ³ - 3ab [a+b]
= 10³ - 3 × 21 [ 10 ]
= 1000 - 63 × 10
= 370
Hence ,
a³ + b³ = 370
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