2x2 + 8x - 12 = 0
4 + 8x - 12 = 0
8x = 12 - 4
8x = 8
x = 1
Answer:
- Josh's book lands first
- Ben's lands about 0.648 seconds later
Step-by-step explanation:
Using the given equation for v=60 and s=40, the height of Ben's book is ...
h(t) = -16t² +60t +40
We want to find t when h(t) = 0, so we're looking for the solution to ....
0 = -16t² +60t +40
Using the quadratic formula, we find the positive value of t to be ...
t = (-60 -√(60² -4(-16)(40)))/(2(-16)) = (15 +√385)/8 ≈ 4.3277
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Similarly, the height of Josh's book is ...
0 = -16t² +48t +40
t = (-48 -√(48² -4(-16)(40)))/(2(-16)) = (12 +√304)/8 ≈ 3.6794
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The time before Josh's book lands is shorter by ...
4.3277 -3.6794 ≈ 0.6482 . . . . . seconds
Josh's book reaches the ground first, by about 0.648 seconds.
Answer:
the cost of increase is $5.00
Answer:
a = 30
b = 40
C
Step-by-step explanation:
This requires that you use a proportion.
a / (a + 15) = 40 / 60
The small triangle's sides are in proportion to the large triangles sides.
Reduce the right. Divide top and bottom by 20
a/(a + 15) = 40/20 // 60/20
a/(a + 15) = 2/3
Cross multiply
3a = 2(a + 15) Remove the brackets on the right.
3a = 2a + 30
Subtract 2a from both sides
3a-2a = 30
a = 30
Find B
b is done exactly the same way.
b/(b+20) = 2/3
3b = 2b + 40
3b - 2b = 40
b = 40