Question 63

A positive number when decreased by 4, is equal to 21 times the reciprocal of this number. The number is:

Solution

Let the number be $$x$$

According to ques,

=> $$(x-4)=21 \times \frac{1}{x}$$

=> $$x^2-4x-21=0$$

=> $$x^2-7x+3x-21=0$$

=> $$x(x-7)+3(x-7)=0$$

=> $$(x-7)(x+3)=0$$

=> $$x=7,-3$$

$$\because$$ $$x$$ is positive, thus $$x \neq -3$$

$$\therefore$$ Number = $$7$$

=> Ans - (B)

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