1. **State the problem:** We have three functions: $f(x) = 4x + 5$, $g(x) = 2x^2$, and $h(x) = 7 - 2x$. We want to find the compositions $hg(x)$, $fh(x)$, $fgh(x)$, and $hh(x)$.
2. **Recall function composition:** For functions $a(x)$ and $b(x)$, the composition $a(b(x))$ means substitute $b(x)$ into $a$.
3. **Calculate $hg(x)$:** This means $h(g(x))$. Substitute $g(x) = 2x^2$ into $h(x) = 7 - 2x$.
$$hg(x) = h(g(x)) = 7 - 2(2x^2) = 7 - 4x^2$$
4. **Calculate $fh(x)$:** This means $f(h(x))$. Substitute $h(x) = 7 - 2x$ into $f(x) = 4x + 5$.
$$fh(x) = f(h(x)) = 4(7 - 2x) + 5 = 28 - 8x + 5 = 33 - 8x$$
5. **Calculate $fgh(x)$:** This means $f(g(h(x)))$. First find $h(x)$, then $g(h(x))$, then $f(g(h(x)))$.
- $h(x) = 7 - 2x$
- $g(h(x)) = 2(7 - 2x)^2$
Expand $(7 - 2x)^2 = 49 - 28x + 4x^2$. So
$$g(h(x)) = 2(49 - 28x + 4x^2) = 98 - 56x + 8x^2$$
Now substitute into $f$:
$$f(g(h(x))) = 4(98 - 56x + 8x^2) + 5 = 392 - 224x + 32x^2 + 5 = 397 - 224x + 32x^2$$
6. **Calculate $hh(x)$:** This means $h(h(x))$. Substitute $h(x) = 7 - 2x$ into $h$.
$$hh(x) = h(h(x)) = 7 - 2(7 - 2x) = 7 - 14 + 4x = -7 + 4x$$
**Final answers:**
- $hg(x) = 7 - 4x^2$
- $fh(x) = 33 - 8x$
- $fgh(x) = 397 - 224x + 32x^2$
- $hh(x) = -7 + 4x$
Function Compositions 0Dbd50
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