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NO LINKS!! URGENT HELP PLEASE!!

Please help me with #25 and 26​

NO LINKS!! URGENT HELP PLEASE!! Please help me with #25 and 26​-example-1

1 Answer

3 votes

Answer:


\textsf{25)} \quad y=6\cdot 2^x


\textsf{26)}\quad y=3\cdot 7^x

Explanation:

The general form of an exponential function is:


\boxed{y=ab^x+c}

where:

  • a is the initial value (y-intercept).
  • b is the base (growth/decay factor) in decimal form.
  • y=c is the horizontal asymptote.
  • x is the independent variable.
  • y is the dependent variable.

As the asymptote is y = 0 for both equations, the general function to use is:


\boxed{y=ab^x}

To write the equation of an exponential function that passes through the given pairs of points, substitute both points into the exponential function and solve to find the values of a and b.


\hrulefill

Question 25

Given points:

  • (0, 6)
  • (3, 48)

Substitute point (0, 6) into the formula and solve for a:


\begin{aligned}y&=ab^x\\\implies 6&=ab^0\\6&=a(1)\\a&=6\end{aligned}

Substitute the found value of a and the point (3, 48) into the formula and solve for b:


\begin{aligned}y&=ab^x\\\implies48&=6b^3\\8&=b^3\\b&=\sqrt[3]{8}\\b&=2\end{aligned}

Therefore, the exponential equation with asymptote y = 0 that passes through points (0, 6) and (3, 48) is:


\boxed{y=6\cdot 2^x}


\hrulefill

Question 26

Given points:

  • (1, 21)
  • (2, 147)

Substitute point (1, 21) into the formula, and point (2, 147) into the formula, to create two equations:


21=ab^1 \implies ab=21


147=ab^2 \implies ab^2=147

Divide the second equation by the first equation to eliminate a and solve for b:


(ab^2)/(ab)=(147)/(21)


(b^2)/(b)=7


b=7

Substitute the found value of b into the first equation and solve for a:


\begin{aligned}ab&=21\\7a&=21\\a&=3\end{aligned}

Substitute the found values of a and b into the formula to write an exponential equation with asymptote y = 0 that passes through points (1, 21) and (2, 147):


\boxed{y=3\cdot 7^x}

User Valter Minute
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