一道数学不等式计算题X(X^2+1≥(X+1)(X^2-X+1){1-2X>3(X-9)

Question

一道数学不等式计算题
X(X^2+1≥(X+1)(X^2-X+1)
{
1-2X>3(X-9)

Answer 1

根据X(X^2+1)≥(X+1)(X^2-X+1)
X(X^2+1) - (X+1)(X^2-X+1)＞0
X^3+X-(X^3+1)＞0
X-1＞0
X＞1
根据1-2X>3(X-9)
1-2X>3X-27
5X＜28
X＜28/5
∴1＜X＜28/5