1.

If [5x + 1/(3x)] = (-10/3); find the value of [(3x)3 + 1/(5x)3]?1. -4.42. -4.83. -44. -4.2

Answer» Correct Answer - Option 1 : -4.4

Given:

[5x + 1/(3x)] = (-10/3)

Calculation:

∵ [5x + 1/(3x)] = (-10/3)

Multiplying both side with 3/5;

⇒ 3/5 × [5x + 1/(3x)] = 3/5 × (-10/3)

⇒ [(3/5) × (5x)] + [(3/5) × (1/3x)] = (-2)

⇒3x + (1/5x) = (-2)

Cube both side;

⇒ (3x)3 + (1/5x)3 + 3 × (3x) × (1/5x) × [3x + (1/5x)] = (-8)

⇒ (3x)3 + (1/5x)3 + [9/5 × (-2)] = (-8)

⇒ (3x)3 + (1/5x)3 – (18/5) = (-8)

⇒ (3x)3 + (1/5x)3 = (-8) + (18/5)

⇒ (3x)3 + (1/5x)3 = [(-40) + 18]/5

⇒ (3x)3 + (1/5x)3 = (-22)/5

⇒ (3x)3 + (1/5x)3 = (-4.4)


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