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1. rebecca was asked to create five pairs of like terms. determine if s…

Question

  1. rebecca was asked to create five pairs of like terms. determine if she completed the task correctly and correct any errors.

2.5w and -8w
\\(\frac{1}{2}x\\) and \\(\frac{1}{2}\\)
38 and -15
-7c² and c²
5a and 5b

in questions 2-10, simplify the expressions by combining like terms.

  1. \\(4r + 9r - 11r + 7r\\)
  2. \\(-r + 6 + 8r - 14\\)
  3. \\(-26r + 7r - 15p - 7p\\)
  4. \\(8r + 12p - 7 - 3p\\)
  5. \\(10r - 5r + 3r - 8r\\)
  6. \\(-4p - 2r - 15p\\)
  7. \\(\frac{3}{4}r + 2r + \frac{1}{2}r\\)
  8. \\(1.5r - 3r + 8r + 2.5r\\)
  9. \\(\frac{2}{3}p + \frac{4}{3}p - \frac{1}{3}p\\)
  1. simplify an expression for the perimeter of the rectangle.

diagram of rectangle with height (5w - 2) and width (3w)
perimeter: _______

Explanation:

Response
Question 1: Determine if Rebecca completed the task correctly and correct any errors.

Like terms are terms with the same variable (or no variable for constants) raised to the same power.

  • 2.5w and -8w: Both have variable \( w \), so like terms (correct).
  • \(\frac{1}{2}x\) and \(\frac{1}{2}\): One has variable \( x \), the other is a constant—not like terms (error). Correct: e.g., \(\frac{1}{2}x\) and \(\frac{3}{2}x\), or \(\frac{1}{2}\) and \( 5 \).
  • 38 and -15: Both constants, so like terms (correct).
  • \(-7c^2\) and \( c^2 \): Both have \( c^2 \), so like terms (correct).
  • 5a and 5b: Different variables (\( a \) vs. \( b \))—not like terms (error). Correct: e.g., 5a and 3a, or 5b and -2b.

Combine like terms (all have \( r \)) by adding/subtracting coefficients.

  • Step 1: Add coefficients: \( 4 + 9 - 11 + 7 \).
  • Step 2: Calculate: \( 4 + 9 = 13 \); \( 13 - 11 = 2 \); \( 2 + 7 = 9 \).

Combine like terms: \( r \)-terms and constants.

  • Step 1: Combine \( r \)-terms: \( -r + 8r = 7r \).
  • Step 2: Combine constants: \( 6 - 14 = -8 \).

Answer:

Rebecca made errors in the pairs \(\boldsymbol{\frac{1}{2}x}\) and \(\boldsymbol{\frac{1}{2}}\) (not like terms, as one has \( x \), the other is a constant) and \(\boldsymbol{5a}\) and \(\boldsymbol{5b}\) (not like terms, different variables). Correct pairs could be \(\frac{1}{2}x\) and \(\frac{3}{2}x\) (or other \( x \)-terms) for the second, and \( 5a \) and \( 3a \) (or other \( a \)-terms) for the fifth. The first, third, and fourth pairs are correct.

Question 2: Simplify \( 4r + 9r - 11r + 7r \)