Answer:
3
Step-by-step explanation:
A direct variation is of the form
y = kx
We know x and y so we can find k
81 = k *27
Divide each side by 27
81/27 = 27k/27
3=k
The constant of variation is 3
Step-by-step explanation:
One gallon = 25 miles
8 gallon= 25×8 miles= 200 miles
Answer:
10(3)^x
Step-by-step explanation:
The function contains the points (2,90) and (4,810). Use the general form y=abx to write two equations:
90=ab^2 and 810=ab^4
Solve each equation for a:
a=90/b^2 and a=810/b^4
Since a=a, set the other sides of the equations equal and solve for b.
90/b2=810/b4
Cross multiply, then divide and simplify as follows:
90b^4=810b^2
b^4/b^2=810/90
b^2=90
b^3
Now, use the value of b and the point (2,90) to find the value of a.
90=a(3^2)
a=10
So, substitute answers in original equation for a final answer of f(x)=10(3)^x.
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