Question 71

If $$(x - 7)^3 + (2x + 8)^3 + (2x - 3)^3 = 3 (x — 7) (2x + 8) (2x — 3)$$, then what is the value of $$x$$ ?

Solution

Given, $$(x - 7)^3 + (2x + 8)^3 + (2x - 3)^3 = 3 (x — 7) (2x + 8) (2x — 3)$$

$$=$$> $$(x - 7)^3 + (2x + 8)^3 + (2x - 3)^3 - 3 (x — 7) (2x + 8) (2x — 3)=0$$

We know that if $$a^3+b^3+c^3-3abc=0$$ then $$a+b+c=0$$

$$=$$> $$\left(x-7\right)+\left(2x+8\right)+\left(2x-3\right)=0$$

$$=$$> $$5x-2=0$$

$$=$$> $$x=\frac{2}{5}$$

$$=$$> $$x=0.4$$

Hence, the correct option is Option B

Share on Whatsapp Share on Whatsapp

Create a FREE account and get: