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Let f (x) =x ^(2) + bx + c AA in R, (b,c...

Let `f (x) =x ^(2) + bx + c AA in R, (b,c, in R) ` attains its least value at `x =-1` and the graph of `f (x)` cuts y-axis at `y =2.`
The value of `f (-2) + f(0) + f(1)=`

A

3

B

5

C

7

D

9

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The correct Answer is:
To solve the problem, we need to find the values of \( f(-2) \), \( f(0) \), and \( f(1) \) for the quadratic function \( f(x) = x^2 + bx + c \), given that it attains its least value at \( x = -1 \) and cuts the y-axis at \( y = 2 \). ### Step-by-step Solution: 1. **Identify the y-intercept**: Since the graph of \( f(x) \) cuts the y-axis at \( y = 2 \), we have: \[ f(0) = c = 2 \] 2. **Find the vertex**: The vertex of the quadratic function \( f(x) = x^2 + bx + c \) occurs at \( x = -\frac{b}{2} \). Given that the least value occurs at \( x = -1 \), we set: \[ -\frac{b}{2} = -1 \] Solving for \( b \): \[ b = 2 \] 3. **Write the quadratic function**: Now that we have \( b \) and \( c \), we can write the function: \[ f(x) = x^2 + 2x + 2 \] 4. **Calculate \( f(-2) \)**: Substitute \( x = -2 \) into the function: \[ f(-2) = (-2)^2 + 2(-2) + 2 = 4 - 4 + 2 = 2 \] 5. **Calculate \( f(0) \)**: We already found that \( f(0) = c = 2 \). 6. **Calculate \( f(1) \)**: Substitute \( x = 1 \) into the function: \[ f(1) = (1)^2 + 2(1) + 2 = 1 + 2 + 2 = 5 \] 7. **Sum the values**: Now, we add the values we found: \[ f(-2) + f(0) + f(1) = 2 + 2 + 5 = 9 \] ### Final Answer: \[ f(-2) + f(0) + f(1) = 9 \]
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