Question

plz plz plz plz plz plz plz plz plz plz plz solve these three sums plz solve plz plz plz its very very urgent

Answer 1

Question No 1 question is incomplete,because without knowing the value of xy=? we can't calculate the expression.

$1)4x + 3y = 9 \\ 64 {x}^{3} + 27 {y}^{3} = (( {4x)}^{3} + ( {3y)}^{3} ) \\ = (4x + 3y)(16 {x}^{2} - 12xy + 9 {y}^{2} ) \\ = 9(16 {x}^{2} + 24xy - 24xy - 12xy + 9 {y}^{2} \\ = 9(( {4x + 3y})^{2} - 36xy) \\ = 9(81 - 36xy) \\ put \: the \: value \: of \: xy \: in \: it \: and \: solve \: further$
19)
$( {2x)}^{3} - ( {3y)}^{3} = (2x - 3y)(4 {x}^{2} + 6xy + 9 {y}^{2} ) \\ since \: 2x - 3y = 5 \: \: \: \: \: \: \: xy = 5 \\ = 5(4 {x}^{2} - 12xy + 12xy + 6xy + 9 {y}^{2} ) \\ = 5(4 {x}^{2} - 12xy + 9 {y}^{2} + 18xy) \\ = 5(( {2x - 3y)}^{2} + 18xy) \\ = 5( {5}^{2} + 18 \times 5) \\ = 5(25 + 90) \\ = 5(115) \\ = 575 \: \: \: ans$
20) can't be solved because there is no y term in the expression,even though there is y term in the second half part.