Radioactive materials can be described using half-lives. For every half-life that passes , the amount of radioactive material decreases by 50% . If you begin with 40 grams of material , which function can you use to find y, the amount of the substance that remains after t half- lives ?

256π units²   (answer b)

step-by-step explanation:

the formula for the surface area of a sphere of radius r

is             a = 4πr²

and so, if r = 8 units, then the surface area is:

a = 4π(8 units)² = 256π units²   (answer b)

5/6

step-by-step explanation:

if i remember correctly with perpendicular stuff you just take away the negative

answer is 144

step-by-step explanation: