Answer: Choice B) The expression (10-2x)(30-2x)x represents the volume of the box
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The original width is 10 inches. The width reduces to 10-2x inches after we cut off the top two corners of the rectangle. We can think of it as taking 10 and subtracting off two copies of x like so: 10-x-x = 10-2x
Similarly, the length goes from 30 inches to 30-2x inches. This time we're taking off the top and bottom corners (focus on either side it doesn't matter).
The height of the box is x inches due to this portion being folded up.
Volume of box = (width)*(length)*(height)
Volume of box = (10-2x)(30-2x)x
Note: the units for the answer are in cubic inches which can be written as "in^3" (inches cubed).
Answer: the cost per unit of gas is $0.28
Step-by-step explanation:
Let x represent the cost per unit of electricity.
Let y represent the cost per unit of gas.
During one month, a homeowner used 500 units of electricity and 100 units of gas for a total cost of $333. This is expressed as
500x + 100y = 333 - - - -- - -- - -- -1
The next month, 400 units of electricity and 150 units of gas were used for a total cost of $286. This is expressed as
400x + 150y = 286 - - - - - - - - - --2
Multiplying equation 1 by 400 and equation 2 by 500, it becomes
200000x + 40000y = 133200
200000x + 75000y = 143000
Subtracting, it becomes
- 35000y = - 9800
y = - 9800/- 35000
y = 0.28
Substituting y = 0.28 into equation 2, it becomes
400x + 150 × 0.28 = 286
400x = 286 - 42 = 244
x = 244/400 = 0.61
Answer: √117
Step-by-step explanation:
Since no diagram present, am assuming hypotenuse AB and right angle C. Let side opp angle B be b, and side opposite angle A be a. Altitude CD is x.
a^2 + b^2 = 22^2 (Pythagorean)
Using Pythag on two smaller triangles,
x^2 + 13^2 = a^2
x^2 + 9^2 = b^2
Substituting in first equation,
x^2 + 13^2 + x^2 + 9^2 = 22^2
x^2 = 117, so x = √117
