Question

Find : a³ -
1/a³ if a -1/a = 4
.​

Answer 1

$\Huge\bf\maltese{\underline{\green{Answer°᭄}}}\maltese$

$\large\bf{\underline{\red{GIVEN:-}}}$

a-1/a=4

$\large\bf{\underline{\red{TO \:FIND:-}}}$

a³ - 1/a³

$\large\bf{\underline{\red{SOLUTION:-}}}$

Square on both sides,

(a-1/a)²=4²

a²+1/a²-2a.1/a-16

a²+1/a²-2=16

a²+1/a²=14

a³-b³=(a-b)(a²+b²+ab)

Using this formula we get,

a³-1/a3 = (a-1/a)(a²+1/a²+a.1/a)

=4(14+1)

=4*15=60

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