Question

x^2-(9-x)^2>-2x и 4 еще

Answer 1

$2)\;x^2-(9-x)^2<-2x\\x^2-81+18x-x^2+2x<0\\20x<81\\x=\frac{81}{20}\\x<4\frac1{20}\\\\\\4)\;x^2<(25-x)^2+25x\\x^2<625-50x+x^2+25x\\25x<625\\x<25$