Question

( 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] )

# Illustration - 17 Solve x4 - 2x2 - 63 50

Solution