A 256-gallon barrel of radioactive Urikium is spilled at a factory. The entire area is evacuated! Experts say that the area can be deemed safe after only 2 gallons remain. Unfortunately, it is too toxic for any clean-up efforts, so residents will just have to wait for the Urikium to evaporate, Fortunately, Urikium has a half-life of only three hours. That means that half of the Urikium will evaporate every three hours HELP

-4

step-by-step explanation:

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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