Expressions
Simplify:
5x+3x−2+7
8x+5
−2x+5=9
x=−2
2x+6=x+9
x=3
One, No, or Infinite Solutions.
Show work/explain to group for full credit.
x+5=12
One Solution
x=7
1) Explain the error
2) What is the correct answer
A student says:
3x + 2x = 5x^2
They multiplied instead of combining like terms
Correct answer: 5x
Simplify:
6(x−1)−2x
4x−6
3x−8=−2
x=2
−3x+6=x+4
x=1/2 or 1.5
One, No, or Infinite Solutions.
Show work/explain to group for full credit.
2(x+3)=2x+9
No Solution
1) Explain the error
2) What is the correct answer
A student expands:
2(x+4)=2x+4
They forgot to distribute to both terms
Correct: 2x+8
Factor:
10x+20+5x
15x+20 = 5(3x+4)
(x/-4)+3=−1
x=16
4(x+1)=2(x+5)
x=3
One, No, or Infinite Solutions.
Show work/explain to group for full credit.
4(x+2)=4x+8
Infinite Solutions
1) Explain the error
2) What is the correct answer
Solve attempt:
2(x+5)=12
x=3.5
Student forgot to expand to the 5
Correct: x=1
Simplify:
−3(x+4)+2(x+1)
−x−10
−5x−7=18
x=−5
−2(x+5)=3(x−1)
x=-7/5 or -1and2/5 or -1.4
One, No, or Infinite Solutions.
Show work/explain to group for full credit.
3x-5=2x+1
One Solution
x=6
1) Explain the error
2) What is the correct answer
A student solves:
2x+3=2x+7 → one solution: x=4
Variables cancel so 3=7
No solution
A rectangle has length x+3 and width 2.
Write and simplify an expression for the perimeter.
2x+10
Show your work both ways, dividing and distributing:
3(-x+4)=9
x=1
3(x−4)=−2(x+5)
x=2/5 or 0.4
One, No, or Infinite Solutions.
Show work/explain to group for full credit.
-2(x+3)=-2x-6
Infinite Solutions
1) Explain the error
2) What is the correct answer
Solve for x.
Find the value for x when dealing with a rectangle. The perimeter is 2x. The length of the rectangle is 2x-9 and the width of the rectangle is x+1.
Student answer: x= 8
Student forgot to double the width and length.
Correct answer x = 4