Question

I have no idea were to begin
If the graph of an equation of the form y=ab^x goes through (2,18)(5,60.75) then a= b=
Help!!!!!

Answer 1

you'll need to plug both those points into the equation to get two equations with two variables.... then solve the system...

Answer 2

*solve for a, b

Answer 3

Let's plug that first point into the equation: (2, 18) into y=ab^x becomes \(\large 18=a\cdot b^2 \)

this is one of your equations... now do the same for the other point...

Answer 4

5=a*b^60.75 is this right

Answer 5

i think you mixed up your x and y there...

Answer 6

60.75=a*b^5 now good

Answer 7

yes...

Answer 8

now you have two equations with two unknowns.... you can solve this system by substitution....

Answer 9

Ok by doin?

Answer 10

substitution.... try solving for a in the first equation and plug that into the second....

Answer 11

in the first equation, \(\large 18=ab^2 \rightarrow a=\frac{18}{b^2} \)
plug this expression for a into the second equation....

Answer 12

ok I got what you just posted when I did my math. What do I do with the b^5 when plugging into the second equation when solving

Answer 13

you need to simplify the equation you now have.... what is the equation you have?

Answer 14

60.75= (18/b^2)*b^5

Answer 15

ok... simplify that...

Answer 16

42.75=b^7

Answer 17

\(\large 60.75=\frac{18}{\cancel{b^2}^1}\cdot \cancel{b^5}b^3 \)
\(\large 60.75=18\cdot b^3 \)

Answer 18

oh ok so then now it is 42.75=b^3

Answer 19

how did you get 42.75?

Answer 20

60.75-18=42.75

Answer 21

no... you should divide...

Answer 22

3.375=b^3 now

Answer 23

good... do you know what to do from here?

Answer 24

3.375^(1/3)=1.5
b=1.5

Answer 25

good.... now find a...

Answer 26

remember, a = 18/(b^2)

Answer 27

so a=8

Answer 28

good.... now can you write the exponential equation for me?

Answer 29

y=(8)1.5^x

Answer 30

nicely done!!! good work.... :)

Answer 31

thank you and thak you for all your help:)

Answer 32

yw... and one more thing... if you are uncertain if your answer is correct or not, plug in those points again into the equation you now have... i think you'll see that the answer is correct...
bye...