1. There are 9 blue marbles in a box. How many groups of 4 marbles are possible?
2. There are 12 boys in a class. In how many ways can they group
themselves by 6?
3. How many group of 5 red cards can be drawn from a deck of 12 red
cards?
4. In how many ways can 8 students seat in arrow of 5. chairs?
5. How many letters of the word GRACIOUS both begin and end with a
vowel?​

30

step-by-step explanation:

times by times

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

-1   1/6.   you dont subtract the denominators

step-by-step explanation: