已知函数f(x)=ax^2+2ax+4(a>3),若X1f(x2)?/_数学解答

已知函数f(x)=ax^2+2ax+4(a>3),若X1f(x2)?/

人气：148 ℃　时间：2020-02-03 16:32:54

解答

f(x1)-f(x2)
=ax1^2+2ax1+4-(ax2^2+2ax2+4)
=a(x1²-x2²)+a(x1-x2)
=a(x1+x2)(x1-x2)+a(x1-x2)
=a(x1-x2)(x1+x2+1)
∵X1+X2=1-a,a>3
∴1-a