Question
An exponential function passes through the points (2,3), (9,33), (15,K). What is the value of K?
Answers
Steve
y = ab^x
a*b^2 = 3
a*b^9 = 33
a = 3/b^2, so
a*b^9 = 3/b^2 * b^9 = 3b^7 = 33
b = 11^(1/7)
a = 3/11^(2/7)
y = 3/11^(2/7) * 11^(x/7)
= 3*11^((x-2)/7)
y(15) = 3*11^(13/7) = k
a*b^2 = 3
a*b^9 = 33
a = 3/b^2, so
a*b^9 = 3/b^2 * b^9 = 3b^7 = 33
b = 11^(1/7)
a = 3/11^(2/7)
y = 3/11^(2/7) * 11^(x/7)
= 3*11^((x-2)/7)
y(15) = 3*11^(13/7) = k