If $(7x + 3)^3 + ( x - 2)^3 + 27(2x -5)^3 = 9 (7x + 3) ( x-2) (2x - 5), $ then the value of 5x + 3 is :
Answer & explanation
Correct answer: option 1
We know that,
When,
a + b + c = 0 then,
= a3 + b3 + c3 = 3abc or vice versa
= (7x + 3)3 + (x - 2)3 + 33(2x - 5)3 = 3 × (7x + 3) × (x - 2) × 3(2x - 5)
a = 7x + 3, b = x - 2 and c = 3(2x - 5)
Then,
= (7x + 3) + (x - 2) + 3(2x - 5) = 0
= 7x + 3 + x - 2 + 6x - 15 = 0
= 14x - 14 = 0
= x = 1
Then,
= 5x + 3 = 5 × 1 + 3 = 8