Balance It Out
Solve: x+7=15
x=8
Solve:
x/3=6
x=18
Solve:
3x+4=10
What type of solution?
Answer: One solution ( x=2 )
Three more than twice a number is 17. What’s the number?
Answer: x=7
Student solved: 2x+5=15
They wrote:
x=15−5
x=10
What’s the error?
Answer: Forgot to divide by 2
Correct solution: x=5
Solve:
3x−5=16
x=7
Solve:
0.5x+4=12
x=16
Solve:
5x−2=5x+7
What type of solution?
Answer: No solution
The length of a rectangle is 4 more than its width. If the perimeter is 28, find the dimensions.
Answer: Length = 10, Width = 6
Student solved: 3(x−4)=12 .
They wrote:
3x−4=12
3x=16
x=16/3
What’s the error?
Answer:
3x-12=12
x=8
Solve:
2(x+4)=3x
x=8
Solve:
2/5x-1=3
x=10
Solve:
2(x+3)=2x+6
What type of solution?
Answer: Infinite solutions
A father is 3 times as old as his son. In 12 years, the father will be twice as old as his son. How old are they now?
Answer: Father = 36, Son = 12
Student solved: 5x+7=2x+10 .
They got x=3 . Is this correct?
If not, explain their error and find the correct answer
Answer: No
Correct solution: x=1
Solve:
4x−7=3(x+2)
x=13
Solve:
3/4(x−2)=6
x=10
Solve:
6x + 9 = 3(2x + 4)
What type of solution?
Answer: No solution
Two consecutive odd numbers add up to 44. What are they?
Answer: 21 and 23
Student solved: 4x+8=2(2x+4).
They wrote: “This has no solution.”
Do you agree?
Answer: No
It has infinite solutions.
Solve:
5(2x−3)=3(3x−2)
x=-1
Solve:
2/3x+5/6=7/2
x=5
Solve:
7(x−2)=3x−14+4x
What type of solution?
Answer: Infinite solutions
A taxi charges $3 to start plus $1.50 per mile. If the total cost is $18, how many miles was the ride?
Answer: 10 miles
Student solved: 1/2x+3=7.
They got: x=8.
Explain the student's error.
Answer:
Trick question to test attention.
Correct solution: x=8 .