TMUA Y and A Tutoring Paper 2 with Answers and Hints · Question 14

Here is an attempt to solve the inequality $x^4-2x^2-3<0$ by completing the square:

I if and only if $x^4-2x^2+1<4$

II if and only if $(x^2-1)^2<4$

III if and only if $-2<x^2-1<2$

IV if and only if $x^2-1<2$

V if and only if $x^2<3$

VI if and only if $-\sqrt3<x<\sqrt3$

Which of the following statements is true?

AThe argument is completely correct.

BThe first error occurs in line I.

CThe first error occurs in line II.

DThe first error occurs in line III.

EThe first error occurs in line IV.

FThe first error occurs in line V.

GThe first error occurs in line VI.

examday