`(1,3) , (2,12)` Write an exponential function `y=ab^x` whose graph passes through the given points.
The given two points of the exponential function are (1,3) and (2,12).
To determine the exponential function
`y=ab^x`
plug-in the given x and y values.
For the first point (1,3), plug-in x = 1 and y=3.
`3=ab^1`
`3=ab` (Let this be EQ1.)
For the second point (2,12), plug-in x=2 and y=12.
`12=ab^2` (Let this be EQ2.)
To solve the values of a and b, apply the substitution method of system of equations. To do so, isolate the a in EQ1.
`3=ab`
`3/b= a`
Plug-in this to EQ2.
`12=ab^2`
`12=(3/b)b^2`
And, solve for b.
`12=3b`
`12/3=b`
`4=b`
Plug-in this value of b to EQ1.
`3=ab`
`3=a(4)`
And, solve for a.
`3/4=a`
Then, plug-in the values of a and b to the exponential function
`y=ab^x`
So, this becomes:
`y = 3/4*4^x`
Therefore, the exponential function that passes the given two points is `y=3/4*4^x` .
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