At a garage sale, a large bin full of DVDs and CDs are being sold. All the DVDs are the same price, and all the CDs are the same price. Aleah buys 2 DVDs for $6 and 4 CDs for $8. Her friend, Ling, wants to buy 4 DVDs and 2 CDs. How much will Ling have to pay?

Aleah's brother, Pierre, wants to spend $20 on DVDs and CDs. What combination of DVDs and CDs could he buy?

Step-by-step explanation:

$6/(2 DVDs) = $3/DVD, and $8/(4 CDs) = $2/CD

a DVD costs $3

a CD costs $2

Ling bought 4 DVDs and 2 CDs for 4×$3 + 2×$2 = $16.

Pierre bought d DVDs and c CDs for $20.

d is 0, 2, 4, or 6

c = (20-3d)/2

(d,c) = (0,10), (2,7), (4,4), or (6,1)

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

0.50 , 0.75

step-by-step explanation: