Question 247721
1. Find the x and y intercepts, if any, if none exist, state
F(x)=x^2-4x-18
For the y-intercept, set x=0
y = -18 is the y-int.
For x, set y=0:
x^2-4x-18 = 0
*[invoke solve_quadratic_equation 1,-4,-18]

x = 2 + sqrt(22)
x = 2 - sqrt(22)
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2. Use formula 4.9t^2+vot=s to answer the question;
A coin was tossed downward with an initial velocity of 30 meters per second (v0) at an altitude of 402 meters (s). Approximately how long does it take the coin to reach the ground 
This is what I got no sure? 
use 4.9t^2 + vot = s 
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s = -4.9t^2 - 30t + 402 takes it all into account
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Set s = 0 to find when it hits the ground.
-4.9t^2 - 30t + 402 = 0
*[invoke solve_quadratic_equation -4.9,-30,402]


a coin is tossed downward with an initial velocity of 30 meters per second(v0)at an altitude of 402 meters(s). approximately how long does it take the coin to reach the ground? 
-4.9t^2-30t = -402 meters 
4.9t^2 + 30t -402 = 0 
Use Quadratic formula: 
t = [-30 +- sqrt(900 - 4*4.9*-402)]/(9.8) 
t = [-30 +- sqrt(8779.2)]/9.8 
Positive solution:
t = [-30+93.7]/9.2 
t = 6.924 seconds 
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The same method you used, ~0.4 seconds difference somewhere.
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3. Not sure of this one
Translate the problem into a pair of linear equations in 2 variables. Solve the equations using either elimination or substitution. State your answer for the specified variable. 
Roberto invested some money at 7% and then invested $2000 more than twice this amount at 9%. His total annual income from the two investments was $2930. How much did he invest at 9%?
x = amount at 7%
y = amount at 9%
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y = 2x + 2000
0.07x + 0.09y = 2930
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Sub for y
0.07x + 0.09*(2x+2000) = 2930
7x + 18x + 18000 = 293000
25x = 275000
x = $11,000
y = $24,000