Oh phone company offers to monthly plans plan a cost $13 plus an additional $.14 for each minute of calls Plan B cost $18 plus an additional of $.09 for each minute of calls. For what amount of calling do the two plans cost the same?

What is the cost when the two plans cost the same?

For 100 minutes

Step-by-step explanation:

Step one:

given data

Oh phone company

monthly plans plan a cost $13 plus an additional $.14 for each minute of calls

let the number of minutes be x, and the total be y

y= 13+0.14x1

Plan B cost $18 plus an additional of $.09 for each minute of calls

let the number of minutes be x, and the total be y

y= 18+0.09x2

Step two:

Equate 1 and 2 above

13+0.14x=18+0.09x

collect like terms

18-13= 0.14x-0.09x

5=0.05x

divide both sides by 0.05

x=5/0.05

x=100 minutes

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