RRB NTPC Mains or Stage 2 Model Paper 7 with solutions

Question : 15 of 120

Marks: +1, -0

The sum of the square of a number and the square of the reciprocal of the number, is thrice the difference of the square of the number and the square of the reciprocal of the number. What is the number?

1
$(2)^{1/ 4}$
$(3)^{1/ 3}$
$(4)^{1/ 4}$

Validate

Solution:

(b) Let number be x, then its reciprocal be

1/x

.
(a)ccording to question,

x^2+1/x^ 2=3[x^2 -1/x^2]

∴x^ 2+1/x^2= 3x ^2- 3/{x^2} ⇒ 2x^2 = 4/{ x^2}

⇒x^4 = 2 ⇒ x = (2)^{1/ 4}

Go to Question:

Prev Question

Next Question