Please help and if you can explain it please

1) 1/3   2a)2/5  2b)1/2  2c)9/20

Step-by-step explanation:

1) A fair die has 6 sides (1,2,3,4,5,6) so there are 2 sides that are greater than 4. Probability is chance of occurance/total chances so 2/6 which simplifies to 1/3

2) The set is (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19, 20) The prime numbers in that set are (2,3,5,7,11,13,17,19)

a)So the probability that a prime number is picked is 8/20 which simplifies to 2/5

b) The odd numbers are (1,3,5,7,9,11,13,15,17,19) so probability of odd is 10/20 which simplifies to 1/2

c) The single digit numbers are (1,2,3,4,5,6,7,8,9) so the probability is 9/20

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