Cos(-x)=-cos x for all values of x

a) True
b) False

this is false ^.^ lol

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

they charge the same amount at 20 minutes.

step-by-step explanation:

answer: plz mark me brainliest

7 hours, 0 minutes, 0 seconds

or:  

0.04

total weeks

or:  

0.29

total days

or:  

7.00

total hours

or:  

420.00

total minutes

or:  

25,200.00

total seconds

step-by-step explanation: