F = 3/r.
The formula for the volume of a cylinder is
V=πr²h. We know that h=2r, so this gives us:
V = πr²(2r) = 2πr³
The surface area of a cylinder is the sum of the areas of all of the faces. The bottom and top are circles, whose areas are both given by A=πr². The lateral area of a cylinder is given by the circumference multiplied by the height. C = 2πr, and the height is 2r, so the lateral area would be
A=(2πr)(2r)= 4πr². This gives us a total surface area of
SA = 4πr²+πr²+πr² = 6πr².
The ratio of surface area to volume would be:
SA/V = 6πr²/2πr³. After simplifying, we have f=3/r.
Switch y=2x+7 to 2x-y=-7 then multiply that equation by 2 to cancel out the y's. that ends up as 4x-2y=-14 which then you get x=-24. then you substitute x into one of the original equations y= 2(-24)+7 which equals y=-41
Answer: 60 degrees
Step-by-step explanation:
Answer: the cost of each pencil is $0.5
the cost of each eraser is $0.15
Step-by-step explanation:
Let x represent the cost of one pencil.
Let y represent the cost of one eraser.
Becky spent $1.45 for 2 pencils and 3 erasers. This means that
2x + 3y = 1.45- - - - - - - - - -1
Luke spent $2.65 for 5 pencils and 1 eraser. This means that
5x + y = 2.65- - - - - - - - - -2
Multiplying equation 1 by 1 and equation 2 by 3, it becomes
2x + 3y = 1.45
15x + 3y = 7.95
Subtracting, it becomes
- 13x = - 6.5
x = - 6.5/- 13
x = 0.5
Substituting x = 0.5 into equation 2, it becomes
5 × 0.5 + y = 2.65
2.5 + y = 2.65
y = 2.65 - 2.5
y = 0.15
