Unit 4, Lesson 4
Combining Like Terms (Part 2)
Accelerated 7
Practice
Problem 1
- Noah says that \(9x - 2x + 4x\) is equivalent to \(3x\), because the subtraction sign tells us to subtract everything that comes after \(9x\).
- Elena says that \(9x - 2x + 4x\) is equivalent to \(11x\), because the subtraction only applies to \(2x\).
Do you agree with either of them? Explain your reasoning.
Problem 2
Identify the error in generating an expression equivalent to \(4+2x-\frac12(10-4x)\). Then correct the error.
\(4+2x + \frac {\text{-}1}{2}(10 + \text-4x)\)
\(4+2x +\text-5 +2x\)
\(4+2x-5+2x\)
\(\text-1\)
Problem 3
Select all expressions that are equivalent to \(5x -15 - 20x+10\).
\(5x - (15+20x) + 10\)
\(5x+\text-15+\text-20x+10\)
\(5(x-3-4x+2)\)
\(\text-5(\text-x +3+4x+\text-2)\)
\(\text-15x-5\)
\(\text-5(3x+1)\)
\(\text-15(x - \frac13)\)
The school marching band has a budget of up to \$750 to pay for 15 new uniforms and competition fees that total \$300. How much can they spend on each uniform?
- Write an inequality to represent this situation.
- Solve the inequality and describe what it means in the situation.
Problem 5
Solve the inequality that represents each story. Then interpret what the solution means in the story.
- Each time Elena earns \$9, she gives \(x\) dollars to charity. Elena believes this will happen 7 times this month. She wants to be sure she keeps at least \$42 from this month’s earnings. \(7(9-x) \geq 42\)
- Lin buys a candle that is 9 inches tall and burns down \(\frac37\) inch per minute. She wants to let the candle burn down until it is less than 6 inches tall. \(9 - \frac{3}{7}x < 6\)
Problem 6
If two angles are both vertical and supplementary, can we determine the angles? Is it possible to be both vertical and complementary? If so, can you determine the angles? Explain how you know.