Unit 2 Mid Unit Study Guide

Elena has $225 in her bank account. She takes out $20 each week for w weeks. After w weeks she has d dollars left in her bank account. Write an equation that represents the amount of money left in her bank account after w weeks. (2.3 #7)

• d = 20w

• d = 225-20w

• d = 20-225w

Which equations is equivalent to the equation 6x + 9 = 12? (2.6 #1)

• x + 9 = 6

• 2x + 3 = 4

• 3x + 9 = 6

• 6x + 12 = 9

• 12x + 18 = 24

Which equation has the same solution as 10x - x + 5 = 41? (2.9 #8)

Graph the equations y=4x+2 and 4x-3y=12 on the grid.

Answer explanation

A school sells adult tickets and student tickets for a play. It collects $1,400 in total. The graph shows the possible combinations of the number of adult tickets sold and the number of student tickets sold. What does the vertical intercept (0, 200) tell us in this situation? (2.11 #10)

• It tells us the decrease in the sale of adult tickets for each student ticket sold

• It tells us the decrease in the sale of student tickets for each adult ticket sold

• It tells us that if no adult tickets were sold, then 200 student tickets were sold

• It tells us that if no student tickets were sold, then 200 adult tickets were sold

Here is a system of equations, state what changes would you do to either one of the equations to be eliminate one of the variables: 

2x-3y=12

x+y=5

• add the equations to eliminate the x variable

• Multiply the first equation by 2, then add the equations to eliminate the x variable

• Multiply the second equation by 2, then subtract the equations to eliminate the x variable

• Multiply the second equation by 2, then add the equations to eliminate the x variable

Which statement explains why 13x - 13y = -26 shares a solution with this system of equations: (2.15 #4)

• Because 13 x − 13 y = - 26 is the product of the two equations in the system of equations, it the must share a solution with the system of equations.

• The three equations all have the same slope but different y -intercepts. Equations with the same slope but different y -intercepts always share a solution.

• Because 10 x − 3 y is equal to 29, I can add 10 x − 3 y to the left side of - 3 x + 10 y = 55 and add 29 to the right side of the same equation. Adding equivalent expressions to each side of an equation does not change the solution to the equation.

• Because - 3 x + 10 y is equal to 55, I can subtract - 3 x + 10 y from the left side of 10 x − 3 y = 29 and subtract 55 from its right side. Subtracting equivalent expressions from each side of an equation does not change the solution to the equation.

Should you use subtraction or addition to solve this system by elimination?

• subtraction

• addition