2. A motorist travels for 20km at one speed, and then increased her speed by 20 kph for next 30 km. How fast was she traveling originally if the total trip took 1 hour?

College Algebra
7th Edition
ISBN:9781305115545
Author:James Stewart, Lothar Redlin, Saleem Watson
Publisher:James Stewart, Lothar Redlin, Saleem Watson
Chapter1: Equations And Graphs
Section1.4: Solving Quadratic Equations
Problem 95E
icon
Related questions
Question

Answer item 2

Example: Two pipes are used to fill a water storage tank. The first pipe can fill the tank
in four hours. The two pipes together can fill the tank in 2 hours less time than the
second pipe alone. How long would it take for the second pipe to fill the tank?
Step 1. Representation of the unknown
Let x = required time for the second pipe to fill the tank.
!= rate of the first pipe
rate of the second pipe
rate of two pipes together
Step 2 Working Equation: Rate of the 1" pipe plus rate of the 20d pipe equals rate of two pipes
together.
r-2
Step 3. Solve for x
4x(x - 2)+=
4x(x-2) Clear the equation
x(x – 2) + 4(x – 2) = 4x
- apply distributive property to simplify
- Factor the quadratic expression
- Equate each factor to zero
x2 – 2x + 4x –8- 4x 0
x2 - 2x – 8 = 0
(x – 4)(x + 2) = 0
x - 4 = 0, x+ 2 = 0
- Solve for x
x = 4, x = -2
Answer: Therefore, it takes 4 hours for the second pipe to fill the tank.
TRY: Solve the following Equations
2. A motorist travels for 20km at one speed, and then increased her speed by 20 kph
for next 30 km. How fast was she traveling originally if the total trip took 1 hour?
Transcribed Image Text:Example: Two pipes are used to fill a water storage tank. The first pipe can fill the tank in four hours. The two pipes together can fill the tank in 2 hours less time than the second pipe alone. How long would it take for the second pipe to fill the tank? Step 1. Representation of the unknown Let x = required time for the second pipe to fill the tank. != rate of the first pipe rate of the second pipe rate of two pipes together Step 2 Working Equation: Rate of the 1" pipe plus rate of the 20d pipe equals rate of two pipes together. r-2 Step 3. Solve for x 4x(x - 2)+= 4x(x-2) Clear the equation x(x – 2) + 4(x – 2) = 4x - apply distributive property to simplify - Factor the quadratic expression - Equate each factor to zero x2 – 2x + 4x –8- 4x 0 x2 - 2x – 8 = 0 (x – 4)(x + 2) = 0 x - 4 = 0, x+ 2 = 0 - Solve for x x = 4, x = -2 Answer: Therefore, it takes 4 hours for the second pipe to fill the tank. TRY: Solve the following Equations 2. A motorist travels for 20km at one speed, and then increased her speed by 20 kph for next 30 km. How fast was she traveling originally if the total trip took 1 hour?
APPLICATION OF QUADRATIC EQUATIONS
MOTION PROBLEMS / WORK PROBLEMS
Motion Problem: Distance = Rate x Time
Formula to be used in solving
Work Problem: Work = Rate x Time
these type of worded problems
Example: A car travels 10kph faster than a truck. The car goes 600 km in 5 hours less time than
it takes the truck to travel the same distance. Find the rate of each vehicle in kilometers per
hour.
d
Step 1. Representation of the unknown
Car
600
x+ 10
600
Let x = rate of the truck
x+ 10
x + 10 = rate of the car
Truck
600
600
Step 2. Working Equation: (Time spent by truck traveling 600 km) minus (time spent by car
traveling 600 km) is 5
600
600
= 5
x+10
Step 3. Solve for x
[600
600
x(x + 10)
5 (x+10)(x) clear the equation
x+10
- combine similar term
- reduce the equation by dividing each term by 5
- Factor the quadratic expression
- equate each factor to zero.
600x + 6000 – 600x = 5x2 + 50x
5x? + 50x – 6000 = 0
x2 + 10x - 1200 = 0
(x + 40)(x – 30) = 0
x + 40 = 0,x –- 30 = 0
- solve for x
x = -40, x = 30
Note: -40 can not be rate of the car because when it comes to the rate should be positive, so
the rate of the car is 30 kph.
Answer: Therefore, the rate of the car is 30 kph and the rate of the truck is 40Okph.
Transcribed Image Text:APPLICATION OF QUADRATIC EQUATIONS MOTION PROBLEMS / WORK PROBLEMS Motion Problem: Distance = Rate x Time Formula to be used in solving Work Problem: Work = Rate x Time these type of worded problems Example: A car travels 10kph faster than a truck. The car goes 600 km in 5 hours less time than it takes the truck to travel the same distance. Find the rate of each vehicle in kilometers per hour. d Step 1. Representation of the unknown Car 600 x+ 10 600 Let x = rate of the truck x+ 10 x + 10 = rate of the car Truck 600 600 Step 2. Working Equation: (Time spent by truck traveling 600 km) minus (time spent by car traveling 600 km) is 5 600 600 = 5 x+10 Step 3. Solve for x [600 600 x(x + 10) 5 (x+10)(x) clear the equation x+10 - combine similar term - reduce the equation by dividing each term by 5 - Factor the quadratic expression - equate each factor to zero. 600x + 6000 – 600x = 5x2 + 50x 5x? + 50x – 6000 = 0 x2 + 10x - 1200 = 0 (x + 40)(x – 30) = 0 x + 40 = 0,x –- 30 = 0 - solve for x x = -40, x = 30 Note: -40 can not be rate of the car because when it comes to the rate should be positive, so the rate of the car is 30 kph. Answer: Therefore, the rate of the car is 30 kph and the rate of the truck is 40Okph.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Recommended textbooks for you
College Algebra
College Algebra
Algebra
ISBN:
9781305115545
Author:
James Stewart, Lothar Redlin, Saleem Watson
Publisher:
Cengage Learning
Algebra and Trigonometry (MindTap Course List)
Algebra and Trigonometry (MindTap Course List)
Algebra
ISBN:
9781305071742
Author:
James Stewart, Lothar Redlin, Saleem Watson
Publisher:
Cengage Learning
Elementary Linear Algebra (MindTap Course List)
Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:
9781305658004
Author:
Ron Larson
Publisher:
Cengage Learning
Glencoe Algebra 1, Student Edition, 9780079039897…
Glencoe Algebra 1, Student Edition, 9780079039897…
Algebra
ISBN:
9780079039897
Author:
Carter
Publisher:
McGraw Hill
College Algebra
College Algebra
Algebra
ISBN:
9781337282291
Author:
Ron Larson
Publisher:
Cengage Learning
Algebra & Trigonometry with Analytic Geometry
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:
9781133382119
Author:
Swokowski
Publisher:
Cengage