Consider two function `y=f(x) and y=g(x)` defined as `f(x)={{:(ax^(2)+b,,0lexle1),(bx+2b,,1ltxle3),((a-1)x+2c-3,,3ltxle4):}` `and" "g(x)={{:(cx+d,,0lexle2),(ax+3-c,,2ltxlt3),(x^(2)+b+1,,3gexle4):}` `lim_(xrarr2) (f(x))/(|g(x)|+1)` exists and f is differentiable at x = 1. The value of limit will be
A
`-2`
B
`-1`
C
0
D
2
Text Solution
AI Generated Solution
The correct Answer is:
To solve the problem, we need to analyze the two piecewise functions \( f(x) \) and \( g(x) \) and find the limit \( \lim_{x \to 2} \frac{f(x)}{|g(x)| + 1} \) given that \( f \) is differentiable at \( x = 1 \).
### Step 1: Analyze the function \( f(x) \)
The function \( f(x) \) is defined as:
\[
f(x) =
\begin{cases}
ax^2 + b & \text{if } 0 \leq x \leq 1 \\
bx + 2b & \text{if } 1 < x \leq 3 \\
(a-1)x + 2c - 3 & \text{if } 3 < x \leq 4
\end{cases}
\]
To ensure \( f(x) \) is continuous at \( x = 1 \):
\[
f(1) = a(1)^2 + b = a + b
\]
\[
\lim_{x \to 1^+} f(x) = b(1) + 2b = 3b
\]
Setting these equal for continuity:
\[
a + b = 3b \implies a = 2b
\]
### Step 2: Ensure differentiability at \( x = 1 \)
The derivative from the left at \( x = 1 \):
\[
f'(x) = \frac{d}{dx}(ax^2 + b) = 2ax \Rightarrow f'(1) = 2a
\]
The derivative from the right at \( x = 1 \):
\[
f'(x) = \frac{d}{dx}(bx + 2b) = b \Rightarrow f'(1) = b
\]
Setting these equal for differentiability:
\[
2a = b
\]
Substituting \( a = 2b \):
\[
2(2b) = b \implies 4b = b \implies b = 0
\]
Thus, \( a = 0 \).
### Step 3: Analyze the function \( g(x) \)
The function \( g(x) \) is defined as:
\[
g(x) =
\begin{cases}
cx + d & \text{if } 0 \leq x \leq 2 \\
ax + 3 - c & \text{if } 2 < x < 3 \\
x^2 + b + 1 & \text{if } 3 \leq x \leq 4
\end{cases}
\]
To ensure continuity at \( x = 2 \):
\[
g(2) = 2c + d
\]
\[
\lim_{x \to 2^-} g(x) = 2c + d
\]
\[
\lim_{x \to 2^+} g(x) = 2a + 3 - c
\]
Setting these equal:
\[
2c + d = 2a + 3 - c \implies 3c + d = 2a + 3
\]
### Step 4: Calculate the limit
Now we need to find \( \lim_{x \to 2} \frac{f(x)}{|g(x)| + 1} \):
- From previous steps, we know \( f(2) = 2b = 0 \) (since \( b = 0 \)).
- For \( g(2) \), we have \( g(2) = 2c + d \).
Thus, we need to evaluate:
\[
\lim_{x \to 2} \frac{0}{|g(2)| + 1} = \frac{0}{|2c + d| + 1} = 0
\]
### Final Answer:
The value of the limit is \( \boxed{0} \).
To solve the problem, we need to analyze the two piecewise functions \( f(x) \) and \( g(x) \) and find the limit \( \lim_{x \to 2} \frac{f(x)}{|g(x)| + 1} \) given that \( f \) is differentiable at \( x = 1 \).
### Step 1: Analyze the function \( f(x) \)
The function \( f(x) \) is defined as:
\[
f(x) =
\begin{cases}
...