2. The mean of 8 numbers is 136.5. The sum of these numbers is (a) 1029 (b) 1209 (c) 1092 (d) 1902. show the full solving process.

n=8

Let the sum be x

Now

mean = sum/n

136.5 = x/8

or, 136.5 × 8 = x

so, x = 1092

So, (c)1092 is the correct answer.

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