When measuring the level of water in a river, +3 means a rise of 3 feet in the level of the water, and -3 means a
drop of 3 feet in the level of water.
a. use a complete sentence to describe what 21-3) means in the context of this problem.
b. calculate 21-3) and write a sentence describing what the answer means in the context of this problem.

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

did you get the answer?

-5, your answer was correct