Question

Please help me solve the question 9

Answer 1

Step-by-step explanation:

3x+1/3x whole cube is 27x cube+1/3xcube

so 8×8×8=502

Answer 2

Step-by-step explanation:

3x + 1/3x = 8 ------(1)

27 is the cube of 3

so cubing equation ( 1 ) on both sides

( a + b ) ^ 3 = a^3 + b^3 + 3a^2b + 3ab^2

= a^3 + b^3 + 3ab(a+b)

27x^3 + 1/27x^3 + 3(3x.1/3x) ( 3x + 1/3x ) = 8^3

27x^3 + 1/27x^3 + 3(8) = 512 ( given 3x + 1/3x = 8 and

3x .1/3x is 1 because 3x and 3x gets cancelled)

so 27x^3 + 1/27x^3 = 512 - 24

= 488