equations and inequalities

Solve for k:

38 + 7k = 8(k + 4)

• k = 6

• k = 8

• k = -6

• k = 1

Solve for a:

-8(-4+a) + 3(2a+1) = -19

• a = 27

• a = -27

• a = 3.86

• a = 1.67

3x + 2(4x - 4) = 3

• 4
• 3
• 2
• 1

5x - 4 + 2x = 3

• 1
• 2
• 3
• 4

7(1 - y) = -3(y - 2)

• x = 1/4
• x = 4
• x = 5

4w + ²/₇ = -⁴/₅

• w=-¹⁹/₇₀
• w⁷⁰/19
• w=¹⁹/₇₀
• w= -⁷⁰/19

What error(s) did this student make?

• Did not combine like terms

• Needed to add 2x instead of subtract

• Should not use inverse operations on the same side of the equal sign

• No errors; the student is correct

What mistake, if any, did this student make?

• S/He needed to subtract 3x from both sides

• S/He needed to drop down a +2 instead of a -2

• S/He did not divide correctly

• No mistakes; x=2 is correct

This student made an error with the disruptive property. What did s/he do wrong?

• You can't drop down a -16; You need to keep it positive

• You should only multiply the -2 & 8m; the 8 should stay the same

• You need to multiply -2 to both parts inside the parenthesis; -2*8m is -16m and -2*8 is -16

• You should divide -2 from both sides first

This student subtracted 2 from both sides of the equation. What should s/he have done?

• Nothing; This is correct

• S/He should have added a -2 to both sides

• S/He should have added 2 to both sides

• Subtracted 2x instead of 2