Question

a^2+b^2=221/100, ab=0.7, a^3+b^3=?​

Answer 1

Answer:

2.869

Step-by-step explanation:

$a^{2}+b^{2}=2.21\\ab=0.7$

$\implies$ $(a+b)^{2}=a^{2}+b^{2}+2ab$

$\implies$ $(a+b)^{2}=2.21+2(0.7)$

$\implies$ $(a+b)^{2}=2.21+1.4$

$\implies$ $(a+b)=\sqrt{3.61}$

$\implies$ $a+b=1.9$

Now substitute the values in a³+b³ formula :

$\implies$ $a^{3}+b^{3}=(a+b)(a^{2}+b^{2}-ab)$

$\implies$ $a^{3}+b^{3}=(1.9)(2.21-0.7)$

$\implies$ $\boxed{a^{3}+b^{3}=2.869}$

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