a+b=11 ,a 2 +b 2 =61 find a 3 +b 3
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a+b =11---(1)
a^2+b^2 =61----(2) we know
(a+b)^2= a^2+b^2+2ab
(11)^2=61+2ab [from (1) and (2)]
121-61=2ab
60=2ab
60/2=ab
30=ab
ab=30----(3)
a^3+ b^3= (a+b)(a^2-ab+b^2)
= 11*(61-30)
=11*31
=341
a^2+b^2 =61----(2) we know
(a+b)^2= a^2+b^2+2ab
(11)^2=61+2ab [from (1) and (2)]
121-61=2ab
60=2ab
60/2=ab
30=ab
ab=30----(3)
a^3+ b^3= (a+b)(a^2-ab+b^2)
= 11*(61-30)
=11*31
=341
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