Question

The graph of g(x) is the graph of f(x)=8x+20 stretched horizontally by a factor of 4.

Which equation describes the function g?

1. g(x)= 8x+5
2. g(x)= 2x+5
3. g(x)= 32x+20
4. g(x)= 2x+20

Answer 1

g(x) = 2x + 20

I hope this helps. (:

Answer 2

`\bf \qquad \qquad \qquad \qquad \textit{function transformations} \\ \quad \\\\ % left side templates \begin{array}{llll} f(x)=&{{ A}}({{ B}}x+{{ C}})+{{ D}} \\ \quad \\ y=&{{ A}}({{ B}}x+{{ C}})+{{ D}} \\ \quad \\ f(x)=&{{ A}}\sqrt{{{ B}}x+{{ C}}}+{{ D}} \\ \quad \\ f(x)=&{{ A}}(\mathbb{R})^{{{ B}}x+{{ C}}}+{{ D}} \\ \quad \\ f(x)=&{{ A}} sin\left({{ B }}x+{{ C}} \right)+{{ D}} \end{array}\\\\ --------------------`


`\bf \bullet \textit{ stretches or shrinks horizontally by } {{ A}}\cdot {{ B}}\\\\ \bullet \textit{ flips it upside-down if }{{ A}}\textit{ is negative}\\ \left. \qquad \right. \textit{reflection over the x-axis} \\\\ \bullet \textit{ flips it sideways if }{{ B}}\textit{ is negative}\\ \left. \qquad \right. \textit{reflection over the y-axis}`


`\bf \bullet \textit{ horizontal shift by }\frac{{{ C}}}{{{ B}}}\\ \left. \qquad \right. if\ \frac{{{ C}}}{{{ B}}}\textit{ is negative, to the right}\\\\ \left. \qquad \right. if\ \frac{{{ C}}}{{{ B}}}\textit{ is positive, to the left}\\\\ \bullet \textit{ vertical shift by }{{ D}}\\ \left. \qquad \right. if\ {{ D}}\textit{ is negative, downwards}\\\\ \left. \qquad \right. if\ {{ D}}\textit{ is positive, upwards}\\\\ \bullet \textit{ period of }\frac{2\pi }{{{ B}}}`

f(x)=8x+20 is just a linear function, to have it "widen horizontally", that means the A component is some amount less than 1.

to expand it 4 times as much as the parent y = x, then

A = 1/4


`\bf f(x)=\stackrel{A}{\cfrac{1}{4}}(\stackrel{B}{8}x\stackrel{C}{+0})\stackrel{D}{+20}\implies f(x)=\cfrac{1}{4}(8x)+20\implies f(x)=2x+20`

graph it if you wish.