Question

plz answer..............?

Answer 1

It is given (2a-3b)=3 and ab=2 .
${(x - y)}^{3} = {x}^{3} - {y}^{3} - 3xy(x - y)$
So
${(2a - b)}^{3} ={ 3}^{3} = 27$
=>
${(2a)}^{3} - {(3b)}^{3} - 3(2a)(3b)(2a - 3b)= 27$
=>
$8 {a}^{3} - 27 {b}^{3} - 6ab(2a - 3b) = 27$
=>
$8 {a}^{3} - 27 {b}^{3} - 6(2)(3) = 27$
=>
$8 {a}^{3} - 27 {b}^{3} = 27 + 36 = 63.$
Value of the required value=63. Hope it helps you...