Question

Find the value of 8x 3 + 27y 3 if 2x +3y =8 and xy = 5.

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Given,

2x+3y=8

xy=5

To find:

8x³+27y³

Solution:

8x³+27y³=(2x)³+(3y)³

we know that,

(a+b)³=a³+b³+3ab(a+b)

a=2x

b=3y

(2x+3y)³=(2x)³+(3y)³+3(2x)(3y)(2x+3y)

(8)³=8x³+27y³+18xy(2x+3y)

512=8x³+3y³+18(5)(8)

512=8x³+3y³+720

512-720=8x³+3y³

(-208)=8x³+3y³

8x³+3y³=(-208)