The battery life of a certain cell phone starts at 8 hours. The battery life decreases at an annual rate of 30%. Write a function that represents the battery life y after x years. After how many years will the battery life of a cell phone be 2 hours?

no i do not : ( what is it?

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step-by-step explanation:

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8

step-by-step explanation:

we have

using a graphing tool

see the attached figure

this is a quadratic equation (vertical parabola) open up

the vertex is a > vertex

the domain of the function is all real > interval (-∞,∞)

the range of the function is the > [-6.125,∞)

the function has two x->   and

the function is increasing over the > (0.25,∞)

the function is decreasing over the > (-∞,0.25)