# How do you write an exponential function of the form y = a b^x the graph of which passes through (-1, 4/5) and (2, 100)?

##### 1 Answer

Jun 12, 2016

#### Explanation:

Plug in

For

#4/5=a(b)^-1" "" "bb((1))#

and for

#100=a(b)^2" "" "bb((2))#

Note that

#4/5=a/b" "" "bb((3))#

We can solve for

#4/5b=a#

We can use

#100=a(b)^2" "=>" "100=4/5b(b)^2#

We can now solve this for

#100=4/5b^3#

Multiplying both sides by

#125=b^3#

#b=5#

Returning to

#4/5=a/b" "=>" "4/5=a/5" "=>" "a=4#