Hey can anyone help with this question?

Step-by-step explanation:

When you learn calculus you'll be able to do this by hand (without a calculator) but for now we have to just kind of guess. We know that 8 x 8 = 64 and 9 x 9 = 81, so the number is between 8 and 9. Since 68 is closer to 64 than it is to 81, the number is closer to 8. Like less than 8.5. 8.1 squared is 65.61, (you can do this by hand...without a calculator) and 8.2 squared is 67.24, and 8.3 squared is 68.89. 8.3 squared is too high while 8.1 squared was too low; the estimation to the nearest tenth is 8.2

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