Happy buys 5 litres of milk on Monday and uses a fifths of it. On Tuesday she uses half of what is left. How many millilitres are left after Tuesday?​

1/2 if she drank out of it already

2000 mL

Step-by-step explanation:

1. The amount of milk left after 1/5 is drank is 4 litres, which is 4000 mL.

2. She drinks half of that, so divide 4000 mL by two.

2000 mL are left after tuesday

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