Thread: Quadratic function and exponential function question!

hi, it's me again. Thanks so much for the help last time.

i have this table of values:
x | y
1 | 20
3 | 320

i have to make a linear, quadratic, and exponential function from these values.
i used y-y1=m(x-x1) for the linear and came up with f(x)= 150x-130

am i supposed to use the quadratic formula to find the quadratic function? i tried but I ended up being unable to find an answer (undefined?). can someone please walk me through this? maybe I just need the values for a, b, and c.

as for the exponential function, i am completely clueless...

as always, i am not allowed to use a calculator for these problems, so i hope someone can guide me through the steps.

Do you have another set of data points for the quadratic?.

As it is, you have





We need one more because we have three variables but only two equations.

Unless, we can assume c=0 and have

Then we have





Then we solve the system and get



For the exponent, we can use





Solve for a and b.

thank you!!!

a problem with the quadratic one... how do i figure out how f(x)=170?
if i do 170= 130x^2 + -20/3x, what are the next steps?

for the exponential one... i came up with a=88.657... probably not right, cuz i don't think it makes sense. help please?
also, how do i find f(x+3)?
sorry for all these questions.