Question

求函数y=x²-5x-6的单调性.

Answer 1

y=x^2-5x-6=(x-5/2)^2-6-25/4=(x-5/2)^2-49/4

函数开口向上,对称轴是x=5/2.

所以,在(-无穷,5/2]上是单调递减,在[5/2,+无穷)上是单调递增.