解不等式 20x-11-10x^2
问题描述:
解不等式 20x-11-10x^2
RT
答
解法1:20x-11-10x^2≤0 10x^2-20x+11≥0x^2-2x+11/10≥0x^2-2x+1-1+11/10≥0(x-1)^2+1/10≥0(x-1)^2≥-1/10由于(x-1)^2≥0所以x为任意实数.解法2:由于-10>0,所以y=20x-11-10x^2是开口向下的抛物线.判断式:20^2-4(...