10(3x-4/x)^2 - 3(3x - 4/x) -7 is equal to :

Question

\(10\big(3x-\frac{4}{x}\big)^2-3\big(3x-\frac4x\big)-7\) is equal to :

Answer 1

(c) \(\big(3x-\frac4x-1\big)\big(30x-\frac{40}{x}+7\big)\)

\(10\big(3x-\frac{4}{x}\big)^2-3\big(3x-\frac4x\big)-7\)

Let 3x - \(\frac4x\) = a. Then, the expression becomes

10a² - 3a - 7

= 10a² - 10a + 7a - 7

= 10a(a - 1) + 7(a - 1)

= (10a + 7)(a - 1)