Answer:
Step-by-step explanation:
This is good! The length of the metal is 20 inches longer than the width. But we fold up 4-inch flaps on each side, so the height of the box is 4 inches, and the length and width will each decrease by 8 inches (4 inches on each side). Since the length and width decrease by the same amount, the length will still be 20 inches longer than the width. So the equations would be:
l = w + 20
vol = l x w x h = 1716 in3
1716 = (w + 20)(w)(4)
1716 = 4w2 + 80w
4w2 + 80w - 1716 = 0
4(w2 + 20w - 429) = 0
4(w + 33)(w - 13) = 0
w + 33 = 0, so w = -33
w - 13 = 0, so w = 13
Since the width can't be negative, the width of the box is 13 and the length is 33 (13 + 20).
But remember, the length and width of the piece of metal are each 8 inches longer than the box, so it was 41 inches by 21 inches.
This is how I'd set it up:
405/20 = 243/x
this means the mpg (miles / gallons) for 1 situation is the same as the mpg for the other situation (because the rate is the same)
then just cross multiply and solve:
405x=243*20 or 405x=4860 or x = 12
he would need 12 gallons of gas for 243 miles
X = 36
simplify both sides of the equation, isolate the variable,
Answer:
X < -3
Step-by-step explanation:
-x will be positive when x < -3
Step-by-step explanation:
so, you got the volume but don't know how to find the surface area ? that is strange for me. what's the problem ?
the surface of a cube or rectangular prism consists of 6 sides that split (for a rectangular prism) into 3 pairs of equal sides :
top and bottom
left and right
front and back
all we need to do is calculate the areas of these 6 rectangles and add them up. that's it.
in our case
top and bottom : 5×4 × 2 = 20×2 = 40 in²
left and right : 4×4 × 2 = 16×2 = 32 in²
front and back : 5×4 × 2 = 40 in²
so, in total, the whole surface area of the prism is
40 + 32 + 40 = 112 in²
