Question

Use the graph to answer the question.

What is the equation shown in the graph? If it passes through (-2,1.28) and (1,2.5)

(1 point)
Responses

y=−2⋅(1.25)x
y is equal to negative 2 times 1 point 2 5 to the x th power

y=2⋅(1.25)x
y is equal to 2 times 1 point 2 5 to the x th power

y=2⋅−(1.25)x
y is equal to 2 times negative 1 point 2 5 to the x th power

y=1.25⋅(2)x
y is equal to 1 point 2 5 times 2 to the x th power

Answer 1

Use y = A·b^x. From the points,
b^3 = 2.5 / 1.28 = 1.953125 = 1.25^3, so b = 1.25.
Then A = 2.5 / 1.25 = 2.

Therefore y = 2·(1.25)^x.