if a+b=3 and a^2+b^2=40 find a^3+b^3
Answers
Answered by
4
we know the formula of a^3 + b^3.i.e,
(a + b )(a^2 + b^2 + ab)..............(1)
Now, (a+b)^2 =a^2 + b^2 +2ab
(3)^2 = 40 + 2ab
9 = 40 + 2ab
2ab = -31
ab = -31/2............(2)
From eq (1)
=(a +b)(a^2 +b^2 +ab)
=3(40 -31/2)
=3(80 -31/2)
=3 ×49/2
=147/2
=73.5 Ans____________
Hope this helps you.☺️☺️☺️
(a + b )(a^2 + b^2 + ab)..............(1)
Now, (a+b)^2 =a^2 + b^2 +2ab
(3)^2 = 40 + 2ab
9 = 40 + 2ab
2ab = -31
ab = -31/2............(2)
From eq (1)
=(a +b)(a^2 +b^2 +ab)
=3(40 -31/2)
=3(80 -31/2)
=3 ×49/2
=147/2
=73.5 Ans____________
Hope this helps you.☺️☺️☺️
Similar questions