Question

已知函数fx=ax*2+2ax+4（a.>0）若x1

Answer 1

f(x)=ax^2+2ax+4=a(x+1)^2-a+4

∵x10

∴f(x1)-f(x2)

=[a(-x2+1)^2-a+4]-[a(x2+1)^2-a+4]

=a(-x2+1+x2+1)(-x2+1-x2-1)

=-4ax2