Solution
Related Formula
For a composite function f(g(x)):
f(g(x)) = (2g(x) + 3)/(5g(x) + 2)Core Logic
Substitute g(x) = (2 - 3x)/(1 - x) into f(x):
f(g(x)) = (2((2 - 3x)/(1 - x)) + 3)/(5((2 - 3x)/(1 - x)) + 2) = (4 - 6x + 3 - 3x)/(10 - 15x + 2 - 2x) = (7 - 9x)/(12 - 17x)For the domain interval [2, 4], calculate the boundary values since the function is monotonic:
f(g(2)) = (7 - 9(2))/(12 - 17(2)) = (-11)/(-22) = (1)/(2) f(g(4)) = (7 - 9(4))/(12 - 17(4)) = (-29)/(-56) = (29)/(56)Thus, the range [α, β] = [(1)/(2), (29)/(56)].
Step 1: Calculate the Difference
β - α = (29)/(56) - (1)/(2) = (29 - 28)/(56) = (1)/(56) (1)/(β - α) = 56Pattern Recognition
When dealing with composite functions of linear fractions, simplify algebraically first. If the resulting function has no vertical asymptote in the specified interval, it is monotonic, and the extreme values occur exactly at the endpoints.
Chapter Mix
Class 11 Mathematics: Sets, Relations and Functions Class 12 Mathematics: Relations and Functions