Jonathan finds a piece of metal that is 2 1/5 inches thick. He files off 3/10 inch. He adds a protective covering to the metal that is 2/10 inch thick. Then, he polishes the metal and removes an additional 1/10 inch. What is the final thickness of the metal?

I have added the page from the book that indicates what I have explained in my ... a scoop of ice cream has a 3-inch radius how tall should the ice cream cone at shop.

Step-by-step explanation:

3.76%

step-by-step explanation:

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15