QUESTION 8. An unknown number is added to 8. The sum is then divided by 9 to give the answer 10. What is the unknown
number?​

82

Step-by-step explanation:

Let the unknown number be x

If an unknown number is added to 8, this is expressed as;

8 + x

If The sum is  then divided by 9 to give the answer 10, then;

(8+x)/9 = 10

Cross multiply

8 + x = 9 * 10

8 + x = 90

x = 90 - 8

x = 82

Hence the unknown number is 82

1. 34

2. 268

3. x=14.4

step-by-step explanation:

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