please help :) Which of these numbers is the greatest? A. 1.9 x 10 to the 5 power B. 9.1 x 10 to the 2 power C. 7.9 x 10 to the 4 power D. 89,900

The answer is A.

Step-by-step explanation:

1.9x10^5= 190000

9.1x10^2= 910

7.9x10^4 =79000

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