Answer:
- x-intercept: (-0.1, 0)
- Horizontal Asymptote: y = -3
- Exponential <u>growth</u>
(First answer option)
Step-by-step explanation:
<u>General form of an exponential function</u>
![y=ab^x+c](https://tex.z-dn.net/?f=y%3Dab%5Ex%2Bc)
where:
- a is the initial value (y-intercept).
- b is the base (growth/decay factor) in decimal form:
If b > 1 then it is an increasing function.
If 0 < b < 1 then it is a decreasing function. - y=c is the horizontal asymptote.
- x is the independent variable.
- y is the dependent variable.
Given <u>exponential function</u>:
![y=4(10)^x-3](https://tex.z-dn.net/?f=y%3D4%2810%29%5Ex-3)
<h3><u>x-intercept</u></h3>
The x-intercept is the point at which the curve crosses the x-axis, so when y = 0. To find the x-intercept, substitute y = 0 into the given equation and solve for x:
![\begin{aligned}& \textsf{Set the function to zero}:& 4(10)^x-3 &=0\\\\& \textsf{Add 3 to both sides}:& 4(10)^x &=3\\\\& \textsf{Divide both sides by 4}:& 10^x &=\dfrac{3}{4}\\\\& \textsf{Take natural logs of both sides}:& \ln 10^x &=\ln\left(\dfrac{3}{4}\right)\\\\& \textsf{Apply the power log law}:&x \ln 10 &=\ln\left(\dfrac{3}{4}\right)\\\\& \textsf{Divide both sides by }\ln 10:&x&=\dfrac{\ln\left(\dfrac{3}{4}\right)}{\ln 10} \\\\& \textsf{Simplify}:&x&=-0.1\:\:\sf(1\:d.p.)\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%26%20%5Ctextsf%7BSet%20the%20function%20to%20zero%7D%3A%26%204%2810%29%5Ex-3%20%26%3D0%5C%5C%5C%5C%26%20%5Ctextsf%7BAdd%203%20to%20both%20sides%7D%3A%26%204%2810%29%5Ex%20%26%3D3%5C%5C%5C%5C%26%20%5Ctextsf%7BDivide%20both%20sides%20by%204%7D%3A%26%2010%5Ex%20%26%3D%5Cdfrac%7B3%7D%7B4%7D%5C%5C%5C%5C%26%20%5Ctextsf%7BTake%20natural%20logs%20of%20both%20sides%7D%3A%26%20%5Cln%2010%5Ex%20%26%3D%5Cln%5Cleft%28%5Cdfrac%7B3%7D%7B4%7D%5Cright%29%5C%5C%5C%5C%26%20%5Ctextsf%7BApply%20the%20power%20log%20law%7D%3A%26x%20%5Cln%2010%20%26%3D%5Cln%5Cleft%28%5Cdfrac%7B3%7D%7B4%7D%5Cright%29%5C%5C%5C%5C%26%20%5Ctextsf%7BDivide%20both%20sides%20by%20%7D%5Cln%2010%3A%26x%26%3D%5Cdfrac%7B%5Cln%5Cleft%28%5Cdfrac%7B3%7D%7B4%7D%5Cright%29%7D%7B%5Cln%2010%7D%20%5C%5C%5C%5C%26%20%5Ctextsf%7BSimplify%7D%3A%26x%26%3D-0.1%5C%3A%5C%3A%5Csf%281%5C%3Ad.p.%29%5Cend%7Baligned%7D)
Therefore, the x-intercept is (-0.1, 0) to the nearest tenth.
<h3><u>Asymptote</u></h3>
An <u>asymptote</u> is a line that the curve gets infinitely close to, but never touches.
The <u>parent function</u> of an <u>exponential function</u> is:
![f(x)=b^x](https://tex.z-dn.net/?f=f%28x%29%3Db%5Ex)
As<em> </em>x approaches -∞ the function f(x) approaches zero, and as x approaches ∞ the function f(x) approaches ∞.
Therefore, there is a horizontal asymptote at y = 0.
This means that a function in the form
always has a horizontal asymptote at y = c.
Therefore, the horizontal asymptote of the given function is y = -3.
<h3><u>Exponential Growth and Decay</u></h3>
A graph representing exponential growth will have a curve that shows an <u>increase</u> in y as x increases.
A graph representing exponential decay will have a curve that shows a <u>decrease</u> in y as x increases.
The part of an exponential function that shows the growth/decay factor is the base (b).
- If b > 1 then it is an increasing function.
- If 0 < b < 1 then it is a decreasing function.
The base of the given function is 10 and so this confirms that the function is increasing since 10 > 1.
Learn more about exponential functions here:
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