Question

Illustration - 17 Solve x4 - 2x2 - 63 50

JEE/Engineering Exams

Maths

Solution

198

4.0 (1 ratings)

( x^{2}=t Rightarrow t^{2}-9 t+7 t-63 leqslant 0 ) ( (t-9)(t+7) leqslant 0 ) ( left(x^{2}-9right)left(frac{x^{2}+7}{70 e}right) leq 0 ) ( x^{2} leqslant 9 ) ( x leqpm 3 ) ( x in[-3,3] )