Math Problem Statement
f(x) = x^2 - 4x + 3, g(x) = 2x - 1. Solve (i) f(x) = 0, (ii) f(x) = g(x), (iii) g(f(-2)), (iv) f(g(x)).
Solution
Given Information:
- f(x)=x2−4x+3
- g(x)=2x−1
We are solving the following tasks:
(i) Solve f(x)=0
(ii) Solve f(x)=g(x)
(iii) Find g(f(−2))
(iv) Find f(g(x))
Solution:
(i) Solve f(x)=0:
Set f(x)=x2−4x+3=0.
Factorizing the quadratic:
x2−4x+3=(x−1)(x−3)=0
So, x=1 and x=3.
(ii) Solve f(x)=g(x):
Equate f(x)=g(x):
x2−4x+3=2x−1
Rearrange terms:
x2−6x+4=0
Factorizing x2−6x+4 using the quadratic formula:
x=2a−b±b2−4acwhere a=1,b=−6,c=4
x=2(1)−(−6)±(−6)2−4(1)(4)=26±36−16=26±20=26±25
x=3±5
Thus, x=3+5 and x=3−5.
(iii) Find g(f(−2)):
First, calculate f(−2):
f(−2)=(−2)2−4(−2)+3=4+8+3=15
Now substitute f(−2)=15 into g(x):
g(15)=2(15)−1=30−1=29
So, g(f(−2))=29.
(iv) Find f(g(x)):
Substitute g(x)=2x−1 into f(x):
f(g(x))=f(2x−1)
f(2x−1)=(2x−1)2−4(2x−1)+3
Expand (2x−1)2:
(2x−1)2=4x2−4x+1
Substitute into f(g(x)):
f(g(x))=4x2−4x+1−8x+4+3
Simplify:
f(g(x))=4x2−12x+8
So, f(g(x))=4x2−12x+8.
Final Answers:
(i) x=1, x=3
(ii) x=3+5, x=3−5
(iii) g(f(−2))=29
(iv) f(g(x))=4x2−12x+8
Do you want details for any step?
Here are 5 related questions to deepen your understanding:
- How do we determine the roots of a quadratic equation using factorization?
- What is the quadratic formula, and when is it used?
- How can we verify the solutions of f(x)=g(x)?
- What happens if g(x) is a higher-degree polynomial?
- How do we interpret f(g(x)) in the context of composition of functions?
Tip: Always check your solutions by substituting them back into the original equations!