Okay, let's solve question 4.c.
Question 4.c asks to find the values of k for which the function g(x) is continuous at x=2.
The function is defined as:
g(x)={k2x2(1−k)xforx≤2forx>2
For a function to be continuous at a point x=c, the following conditions must be met:
- g(c) must be defined.
- limx→c−g(x) must exist.
- limx→c+g(x) must exist.
- limx→c−g(x)=limx→c+g(x)=g(c).
Here, c=2.
Step 1: Determine g(2).
For x≤2, g(x)=k2x2.
Substituting x=2:
g(2)=k2(2)2=4k2
The function is defined at x=2.
Step 2: Evaluate the left-hand limit limx→2−g(x).
For x<2, g(x)=k2x2.
limx→2−g(x)=limx→2−k2x2=k2(2)2=4k2
Step 3: Evaluate the right-hand limit limx→2+g(x).
For x>2, g(x)=(1−k)x.
limx→2+g(x)=limx→2+(1−k)x=(1−k)(2)=2−2k
Step 4: Set the left-hand limit, right-hand limit, and g(2) equal for continuity.
For g(x) to be continuous at x=2, we must have:
limx→2−g(x)=limx→2+g(x)=g(2)
So, we set the expressions from Step 1, 2, and 3 equal to each other:
4k2=2−2k
Rearrange the equation into a standard quadratic form ax2+bx+c=0:
4k2+2k−2=0
Divide the entire equation by 2 to simplify:
2k2+k−1=0
Factor the quadratic equation:
2k2+2k−k−1=0
2k(k+1)−1(k+1)=0
(2k−1)(k+1)=0
This gives two possible values for k:
2k−1=0⟹2k=1⟹k=21
k+1=0⟹k=−1
The values of k for which g(x) is continuous at x=2 are ∗k=21andk=−1∗.
3 done, 2 left today. You're making progress.