Maths / Cube and Cube Roots / Properties of Cubes of Numbers

QUESTION

The cube of a number X number is nine time of X , then find X , where x $\neq$ 0 and x $\neq$  - 3.

 OPTIONS A. 8 B. 2 C. 4 D. 3
Right Option : D

EXPLANATION
Explain TypeExplanation Content
Text

It is given that, $x^3$ = 9x, x $\neq$ 0, x $\neq$ -3

Now, $x^3$ - 9x = 0 $\rightarrow$ x $(x^2-9)$ = 0

$\rightarrow$ $x^2$ - n9 = 0 ($\because$ x $\neq$ 0) $\rightarrow$ $x^2$ = 9 $\rightarrow$ x = 3 or -3

But x $\neq$ -3 $\therefore$ x = 3

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