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Here are a few recommended readings before getting started with this lesson.
Tiffaniqua's class is taking part in a simulated stock market project to learn about investing money. Every student starts with the same amount of money and their task is to make as much money as possible in three weeks!
Tiffaniqua invested all her money into one stock. After the first week, her stock was worth $65 more! After the second week, her stock was worth twice its value after the first week. During the last week of the project, the value of her stock fell by $50, making Tiffaniqua's stock worth $280.
When solving equations, sometimes more than one step is needed. Both the number of steps and the operations required depend on the complexity of the given equation. For example, consider the following pair of equations.
rl Equation (I):& 3/2(x-2)+5 = 14 [0.8em] Equation (II):& y+2y-4 = 11-2y
The general idea is to simplify both sides of the equation and then isolate the variable on one side of the equation. This is usually done by collecting all the variable terms on one side of the equations and combining them. Then, the operations applied to the variable are undone in reverse order.
Distribute 3/2
a/2* 2 = a
Add terms
LHS * 2/3=RHS* 2/3
Commutative Property of Multiplication
a/b* b/a=1
1* a=a
a*b/c= a* b/c
Multiply
Calculate quotient
LHS+2y=RHS+2y
Commutative Property of Addition
Add terms
Tiffaniqua and her friend Kevin are talking about the stock market project. Kevin is telling her how his investment is doing after two weeks.
Value After First Week: p - 15 The value of the stock tripled the next week. In other words, during the second week, the value of Kevin's investment is three times the value at the first week. Value After First Week:& p - 15 Value After Second Week:& 3(p - 15) If the value of the investment grows by $35 during the last week, it will be $35 more than the value after the second week. Value After First Week:& p - 15 Value After Second Week:& 3(p - 15) Value After Third Week:& 3(p - 15)+35 The final value of Kevin's investment would be $140, which will complete the equation. 3 (p-15) + 35= 140
Distribute 3
Multiply
Add terms
LHS+10=RHS+10
Add terms
.LHS /3.=.RHS /3.
Cross out common factors
Simplify quotient
Calculate quotient
Tearrik and Ramsha both invested the same amount in a single stock. After two weeks, they compared how their investments were doing.
It turns out that after two weeks, both investments are worth exactly the same amount of money!
Value of Tearrik's Investment: 2(m-10) The value of Ramsha's investment grew by a third during the first week, so its value after the first week was 1m+ 13m= 43m. During the second week, the value grew by $10. Then, the value of Ramsha's investment after two weeks is 43m+10. Value of Ramsha's Investment: 4/3m+10 Since the final values of Tearrik's and Ramsha's investments are equal, an equation can be written by setting these two expressions equal to each other. 2(m-10) = 4/3m+10
LHS-4/3m=RHS-4/3m
Commutative Property of Addition
Rewrite 2m as 6/3m
Subtract terms
LHS+20=RHS+20
Add terms
LHS * 3/2=RHS* 3/2
Commutative Property of Multiplication
a/b* b/a=1
a*b/c= a* b/c
Multiply
Calculate quotient
Solve the given equation for the indicated variable. If necessary, round the answer to two decimal places.
Equations with linear terms may have zero, one, or infinitely many solutions. This lesson has already shown how to solve equations with one solution. Now it is time to focus on the other two possibilities.
There are three possible results when solving an equation.
Value of Tiffaniqua's Investment: 2/3t+20 The value of Zosia's investment grew by $30 during the first week, so its value was t+30 at that point. Then the value fell by a third during the second week. This means that the value of Zosia's investment after two weeks is 23(t+30). Value of Zosia's Investment: 2/3(t+30) The values of Tiffaniqua's and Zosia's investments after two weeks are equal. This makes it possible to write an equation that models the given situation. 2/3t+20 = 2/3(t+30)
First Stock: 2(g-10) The second stock doubled its value during the first week, so the value would be 2g at that point. In the second week, the value would grow by $15, so the final value is 2g+15. Second Stock: 2g+15 Ali wants to know how much money invested into both stocks would result in the final values being equal. The best way to find this information is to set the two expressions equal to each other. 2(g-10)=2g+15
Distribute 2/3
a/c* b = a* b/c
Multiply
Calculate quotient
LHS-2/3t=RHS-2/3t
Subtract terms
To solve the challenge presented at the beginning of the lesson, write and solve an equation that models the situation. The challenge stated that during her class simulated stock market project, Tiffaniqua invested all her money into a single stock.
After the first week, Tiffaniqua's investment was worth $65 more than it was at the beginning of the project. After the second week, her stock was worth twice its value after the first week. During the last week of the project, the value of her stock fell by $50, making Tiffaniqua's stock worth $280.
Starting Amount of Money: w Next, the final value of Tiffaniqua's stock can be expressed in terms of w.
The following expression represents final value of Tiffaniqua's stock. Final Value: 2(w+65)-50 Finally, write the equation by setting this expression equal to the final value of the investment, $280. 2(w+65)-50 = 280
.LHS /2.=.RHS /2.
Cross out common factors
Simplify quotient
Calculate quotient