Question Details

If  f ( x ) = { 2 + 2 x , 1 x < 0 1 x 3 , 0 x 3 ; g ( x ) = { x , 3 x 0 x , 0 < x 1 , then range of ( f o g ( x ) ) is

Options

A

[0, 3)

B

[0, 1]

C

[0, 1)

D

(0, 1]

Show Answer

Correct Answer :

Option B

[0, 1]

[0, 1]

Solution :

The correct answer is [0, 1].

Let us determine the range of the composite function (fg)(x) step-by-step.

First, let's analyze the inner function g(x), which is defined as:
g ( x ) = { - x , - 3 x 0 x , 0 < x 1

Let's find the range of g(x) over its domain:
1. For -3x0, we have g(x)=-x. Multiplying the inequality by -1 gives 0-x3, so the range here is [0,3].
2. For 0<x1, we have g(x)=x, so the range here is (0,1].

Combining the two intervals, the overall range of g(x), which serves as the input domain for the outer function f in the composition f(g(x)), is:
Range of g=[0,3]

Now we evaluate f(t) for t[0,3], where t=g(x). Let us look at the definition of f(t):
f ( t ) = { 2 + 2 t , - 1 t < 0 1 - t 3 , 0 t 3

Since the input value t lies in the interval [0,3], it falls completely under the second branch of f(t):
f ( t ) = 1 - t 3

Let us compute the range of 1-t 3 for 0t3:
1. Start with the domain inequality:
0t3
2. Divide all terms by 3:
0t31
3. Multiply by -1 (reversing the inequality signs):
-1-t30
4. Add 1 to all parts of the inequality:
1-11-t31+0
Which simplifies to:
0f(t)1

Thus, the range of (fg)(x) is [0,1].

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