Question

Find the value of 27x 3 + 8y 3 , if 3x + 2y = 20 and xy = 11/9

Answer 1

$\\ = (3x {}^{3} ) \times 3 + (2y { }^{3} ) \times 3 \\ = 3(3 x {}^{3} + 2y {}^{3} ) \\ = 3 \times 20xy \\ = 60 \times 11 \div 9 \\ = 220 \div 3 \\ = 73.3333333.........ans$