If a + b = 2 and a^2 + b^2 = 5, then what is the value of a^3 + b^3 ?
(a) 11
(b) 12
(c) 13
(d) 14
(e) 15
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Algebra
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firdaus117
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(a+b)^2=a^2+b^2+2ab
4=5+2ab
ab=-0.5
a^3 + b^3=(a+ b)(a^2+b^2-ab)
= 4(5+0.5)
=22
I am getting 22 as answer.
4=5+2ab
ab=-0.5
a^3 + b^3=(a+ b)(a^2+b^2-ab)
= 4(5+0.5)
=22
I am getting 22 as answer.
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ajith
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(a+b)^2 = a^2+b^2+2abdtweah wrote:If a + b = 2 and a^2 + b^2 = 5, then what is the value of a^3 + b^3 ?
(a) 11
(b) 12
(c) 13
(d) 14
(e) 15
=> 4 = 5 + 2ab
ab = -0.5
a^3+b^3 = (a+b) (a^2+b^-ab)
= 2(5+0.5)
= 2*5.5
= 11
[spoiler]
A[/spoiler]
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firdaus117
- Master | Next Rank: 500 Posts
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firdaus117 wrote:(a+b)^2=a^2+b^2+2ab
4=5+2ab
ab=-0.5
a^3 + b^3=(a+ b)(a^2+b^2-ab)
= 4(5+0.5)
=22
I am getting 22 as answer.
So close yet so far!!!
