Question

Plz tell this ans in brief
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Answer 1

Step-by-step explanation:

Here, we'll use the given equation to show that;

= (c^6 - 1)/c^3 = 140.

Given, (c^2 - 1)/c = 5; (i)

(c^2 - 1) = 5c; (ii)

Cube the equation (i);

{(c^2 - 1)/c}^3 = (5)^3;

(c^2 - 1)^3 / c^3 = 125;

{c^6 - 1 -3(c^2)(1)(c^2 - 1)} / c^3 = 125; {using the identity (a+b)^3}

{c^6 - 1} /c^3 -3(c^2)(c^2 - 1)/c^3 = 125;

= {c^6 - 1} /c^3 -3(5c)/c = 125; {(c^2-1) = 5c, from equation(ii)}

= {c^6 - 1} /c^3 - 15 = 125;

= (c^6 - 1)/c^3 = 140.

That's all.