Question

Find the value of a if the graph of the exponential function y = a · 2^x passes through the point (3, 128).
Select one:
a. 2
b. 4
c. 8
d. 16

Answer 1

Hey there :)
\[\Large\rm y=a\cdot 2^x\]So we pass through the point \(\Large\rm (x,y)=(3,128)\)
Let's plug it in and solve for a,

Answer 2

\[\Large\rm 128=a\cdot 2^3\]\[\Large\rm 128=a\cdot 8\]Can you finish it up from there? :)

Answer 3

wouldnt it be 128=a*6 not 8

Answer 4

Ah let's be careful with our powers! ^^\[\Large\rm 2^3=\quad 2\cdot2\cdot2=\quad 4\cdot2=\quad 8\]

Answer 5

oh yes
so it would be D 16

Answer 6

yay good job!