Question

Plz help me!

Answer 1

Area of the three equally sized stripes: A

A=(x+15)(x)(3)
A=3x(x+15)
A=3x^2+45x

One gallon of paint will cover an area of no more than 400 square feet: <=400

She only has half of a gallon of paint left:
1/2(400 square feet)=400/2=200 square feet

Inequality that could be used to find the maximum height, in feet, of each stripe:
A<=200
3x^2+45x<=200

Answer: 3x^2+45x <= 200

Could her stripes be 3' tall?
x=3→A=3(3)^2+45(3)=3(9)+135=27+135→A=162<200 Ok
Yes, her stripes could be 3' tall.
Answer: Yes

Could her stripes be 4' tall?
x=4→A=3(4)^2+45(4)=3(16)+180=48+180→A=228>200 No
No, her stripes couldn't be 4' tall.
Answer: No