Find intervals of increasing/decreasing
Find intervals of increasing/decreasing
Last updated at April 19, 2021 by Teachoo
Example 10 Find the intervals in which the function f given by f (x) = x2 β 4x + 6 is (a) strictly increasing (b) strictly decreasingf (π₯) = π₯2 β 4π₯ + 6 Calculate fβ(π) πβ (π₯) = 2π₯ β 4 Calculate fβ(π) = 0 2π₯ β 4 = 0 2π₯ = 4 π₯ = 4/2=2 Hence π₯ = 2 divide real line into 2 disjoint intervals. Plotting points on number line Hence. f is strictly decreasing in interval (β β ,π) f is strictly increasing in interval (2 , β)