Question

a+b=5,ab=6 then a³+b³=?

Answer 1

${(a + b)}^{3} = {a}^{3} + {b}^{3} + 3ab(a + b)$

${5}^{3} = {a}^{3} + {b}^{3} + 3 \times 6(5)$

Answer 2

Answer:

$a^{3}+b^{3}=35$

Step-by-step explanation:

$Given \\a+b=5---(1)\\ab=6---(2)$

/* By algebraic identity:

x³+y³ = (x+y)³-3xy(x+y) */

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

$=5^{3}-3\times 6\times 5$

$=125-90$

$=35$

Therefore,

$a^{3}+b^{3}=35$

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