Let's solve each question one by one.
Question 1:
How many solutions are there to the equation:
\[ 220 = 2x - 12x \]
First, simplify the right side:
\[ 220 = 2x - 12x \]
\[ 220 = -10x \]
Now, solve for \( x \): \[ x = \frac{220}{-10} = -22 \]
Since we obtained a single value for \( x \), there is 1 solution.
Question 2:
Solve the equation for \( x \):
\[ 17x - 8x - 11 = 100 - 30 \]
First, simplify both sides:
\[ 17x - 8x - 11 = 70 \]
\[ 9x - 11 = 70 \]
Now, add 11 to both sides:
\[ 9x = 70 + 11 \]
\[ 9x = 81 \]
Now, divide both sides by 9: \[ x = \frac{81}{9} = 9 \]
So, the answer is x = 9.
Question 3:
How many solutions are there to the equation:
\[ 11x - 99 = 11(x - 9) \]
First, simplify the right side: \[ 11x - 99 = 11x - 99 \]
Both sides are equal, which means the equation is an identity. Therefore, there are infinitely many solutions.
Question 4:
Who is incorrect, and why?
Jimmy's steps:
- \( 9(x - 8) + 3 = -15 \)
- \( 9x - 8 + 3 = -15 \) (Distributive property is incorrect)
- \( 9x - 5 = -15 \)
- \( 9x = -10 \)
Jill's steps:
- \( 9(x - 8) + 3 = -15 \)
- \( 9x - 72 + 3 = -15 \) (Distributive property is correct)
- \( 9x - 69 = -15 \)
- \( 9x = 54 \)
Since Jimmy made an incorrect application of the distributive property and Jill was correct, then Jimmy is incorrect because he used the distributive property incorrectly.
Question 5:
Choose the correct next step and the correct final answer for:
\[ x + 3(3 + x) = 21 + 2x \]
Starting from: \[ x + 3(3 + x) = 21 + 2x \]
Distribute on the left side:
\[ x + 9 + 3x = 21 + 2x \]
Combine like terms:
\[ 4x + 9 = 21 + 2x \]
Move \( 2x \) to the left side:
\[ 4x - 2x + 9 = 21 \]
\[ 2x + 9 = 21 \]
\[ 2x = 21 - 9 \]
\[ 2x = 12 \]
Now divide by 2: \[ x = 6 \]
So, the correct next step is Use the distributive property; x = 6.
Summary of Answers:
- 1
- x = 9
- Infinitely many
- Jimmy is incorrect because he used the distributive property incorrectly.
- Use the distributive property; x = 6