SOLUTION: Find the exponential equation whose graph passes through the points (-2,2/9) and (2,18)? y=

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Question 1137334: Find the exponential equation whose graph passes through the points (-2,2/9) and (2,18)?
y=
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
Find the exponential equation whose graph passes through the points (-2,2/9) and (2,18)?

y=a%2Ab%5Ex
use the points (-2,2%2F9)
2%2F9=a%2Ab%5E%28-2%29
2%2F9=a%2A%281%2Fb%5E2%29
2%2F9=a%2Fb%5E2......solve for a
a=2b%5E2%2F9.......eq.1
use the points (2,18)
18=a%2Ab%5E2......solve for a
a=18%2Fb%5E2.........eq.2
from eq.1 and eq.2 we have
2b%5E2%2F9=18%2Fb%5E2.....solve for b
2b%5E2%2Ab%5E2=18%2A9
b%5E4=18%2A9%2F2
b%5E4=81
b%5E4=3%5E4
b=3
go to a=2b%5E2%2F9.......eq.1 substitute 3 for b
a=%282%2A3%5E2%29%2F9.......eq.1
a=%282%2A9%29%2F9
a=2
so, your exponential equation is: y=2%2A3%5Ex