Skylar repairs microwaves. Her revenue, in dollars, can be modeled by the equation y = 80 + 30x, where x is the number of hours spent repairing microwaves. Her overhead cost, in dollars, can be modeled by the equation y=10x2-20, where x is the number of hours spent repairing microwaves. After how many hours does she break even?

Question

Chanel Carney

Mathematics

12 July, 17:34

Skylar repairs microwaves. Her revenue, in dollars, can be modeled by the equation y = 80 + 30x, where x is the number of hours spent repairing microwaves. Her overhead cost, in dollars, can be modeled by the equation y=10x2-20, where x is the number of hours spent repairing microwaves. After how many hours does she break even?

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Alejandro Randall · Answer 1

after how many hours does she break even?

y = 80 + 30x = 10x2-20

so 10x²-30x-100=0 or x²-3x-10=0

Delta = 3²-4. (1). (-10) = 9+40=49

the root of Delta is sqrt49=7

so x = 3-7/2 = - 2 or x=3+7/2=5

so the number of hours is after x=5 hours