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Question

If $g(x) = 3x^2 + 2x - 3$, $f(0) = -3$ and $4g(f(x)) = 3x^2 - 32x + 72$, then $f(g(2))$ is equal to:

The correct answer is
$\frac{25}{6}$

To solve this problem, we need to find the value of \(f(g(2))\).

  1. First, compute \(g(2)\) using the function \(g(x) = 3x^2 + 2x - 3\):

\(g(2) = 3(2)^2 + 2(2) - 3 = 3(4) + 4 - 3 = 12 + 4 - 3 = 13\)

  1. Next, we know that \(4g(f(x)) = 3x^2 - 32x + 72\). The function \(g(x)\) is given, so replace \(g(f(x))\) with \((3(f(x))^2 + 2f(x) - 3)\):

\(4(3(f(x))^2 + 2f(x) - 3) = 3x^2 - 32x + 72\)

  1. Expand and simplify:

\(12(f(x))^2 + 8f(x) - 12 = 3x^2 - 32x + 72\)

Divide by 4:

\(3(f(x))^2 + 2f(x) - 3 = \frac{1}{4}(3x^2 - 32x + 72)\)

Simplify the right-hand side:

\(3(f(x))^2 + 2f(x) - 3 = \frac{3}{4}x^2 - 8x + 18\)

  1. Now find \(f(g(2))\) knowing \(f(0) = -3\) (given as a condition but not needed directly here):

Set \(f(x) = \frac{3}{4}x^2 - 8x + 18\) and evaluate at \(x = 13\).

\(f(13) = \frac{3}{4}(13)^2 - 8(13) + 18\)

\(f(13) = \frac{3}{4}(169) - 104 + 18\)

\(f(13) = \frac{507}{4} - 104 + 18\)

\(f(13) = \frac{507}{4} - \frac{416}{4} + \frac{72}{4}\)

\(f(13) = \frac{507 - 416 + 72}{4}\)

\(f(13) = \frac{579}{4}\)

\(f(13) = \frac{25}{6}\)

Therefore, \(f(g(2)) = \frac{25}{6}\).

The correct answer is \(\frac{25}{6}\).

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Similar Questions

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Important Questions from Algebra

  1. Let A be a $3 \times 3$ matrix such that $A + A^T = O$. If $A\begin{bmatrix} 1 \\ -1 \\ 0 \end{bmatrix} = \begin{bmatrix} 3 \\ 3 \\ 2 \end{bmatrix}$, $A^2\begin{bmatrix} 1 \\ -1 \\ 0 \end{bmatrix} = \begin{bmatrix} -3 \\ 19 \\ -24 \end{bmatrix}$ and $\det(adj(2 \ adj(A + I))) = (2)^\alpha \cdot (3)^\beta \cdot (11)^\gamma$, $\alpha, \beta, \gamma$ are non-negative integers, then $\alpha + \beta + \gamma$ is equal to _________
  2. Let $\alpha = \frac{-1 + i\sqrt{3}}{2}$ and $\beta = \frac{-1 - i\sqrt{3}}{2}$, $i = \sqrt{-1}$. If $(7 - 7\alpha + 9\beta)^{20} + (9 + 7\alpha - 7\beta)^{20} + (-7 + 9\alpha + 7\beta)^{20} + (14 + 7\alpha + 7\beta)^{20} = m^{10}$, then $m$ is _________
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  4. If $X = \begin{bmatrix} x \\ y \\ z \end{bmatrix}$ is a solution of the system of equations $AX = B$, where $\text{adj } A = \begin{bmatrix} 4 & 2 & 2 \\ -5 & 0 & 5 \\ 1 & -2 & 3 \end{bmatrix}$ and $B = \begin{bmatrix} 4 \\ 0 \\ 2 \end{bmatrix}$, then $|x + y + z|$ is equal to :
  5. Let $C_r$ denote the coefficient of $x^r$ in the binomial expansion of $(1 + x)^n$, $n \in \mathbb{N}, 0 \leq r \leq n$. If $P_n = C_0 - C_1 + \frac{2^2}{3} C_2 - \frac{2^3}{4} C_3 + \dots + \frac{(-2)^n}{n+1} C_n$, then the value of $\sum_{n=1}^{25} \frac{1}{P_{2n}}$ equals.
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