Question

plz send with full method. today is my test

Answer 1

1 )))))
${a}^{3} + \frac{1}{ {a}^{3} }$
$= (a + \frac{1}{a} )^{3} - 3 \times a \times \frac{1}{a} (a + \frac{1}{a} )$
$= {p}^{3} - 3p \: \: (as \: \: \: \: a + \frac{1}{a} = p)$
$= p( {p}^{2} - 3) \: \: \: \: \: \: \: \: proved.$

2 )))))
${a}^{3} + 8 {b}^{3} + 30ab$
$= {a}^{3} + (2b)^{3} + 3 \times a \times 2b \times 5$
$= {a}^{3} + (2b) ^{3} + 3 \times a \times 2b \times (a + 2b)$
$= {(a + 2b)}^{3}$
$= {5}^{3}$
$= 125 \: \: \: \: \: \: \: proved.$