Question

If (3x-4y)=1/2 and xy=1/8 then find value of 27x^3-64y^3....​

Answer 1

Answer:

9/32

Step-by-step explanation:

(3x - 4 y) = 1/2

Cube both the sides ,

(3x-4y)^3 = (1/2)^3

=> 27x^3 - 64y^3 - 3 (3x) (4y) ( 3x - 4y ) = 1/8

=> 27x^3 - 64y^3 = 1/8 × [36xy (3x - 4y)]

Now putting the values in the RHS -

$\frac{1}{8} \times (36 \times \frac{1}{8} \times \frac{1}{2} )$

$\frac{36}{128} = \frac{9}{32}$