An ice cube with the surface area of 60 in^2 is placed in the sun. As it melts, it loses 15% of its surface area each minute. Let y be the surface area of the ice cube x minute after it is placed in the sun.

y =60 (1-0.15)^x

Step-by-step explanation:

Hi, to answer this question we have to write an equation using the information given.

15% = 0.15 (decimal form) =15/100=0.15

We have to multiply the surface if the area (60) by the percent change ( since is a decrease is equal to 1-0.15) to the number of minutes (x)

y =60 (1-0.15)^x

Feel free to ask for more if needed or if you did not understand something.

in simplified version   it would be x ≤-4

step-by-step explanation:

multiply each term in x ≤-4 by -1

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240