Mr. Barkley's solutions are wrong!
Determine the error which was made. Please be specific!
In what step was the error?
What was done incorrectly?
What should have been done instead?
Solve the problem correctly.
1. The problem: 14 = 4x – 2 (x – 5)
Mr. Barkley's solution:
14 = 4x – 2 (x – 5)
14 = 4x – 2x – 10
14 = 2x – 10
24 = 2x
12 = x
Solution: x = 12
2. Problem 2: 7 – 3a < 34
Mr. Barkley's solution:
7 – 3a < 34
- 3a < 27
Solution: a <-9
3. Problem 3:
Thelma has $178 in gift cards at the local hardware store. She plans to use them to buy a new set of wrenches and some welding rods. The wrench set costs $80. The welding rods are $10 per packet. What is the most number of packets of welding rods she will be able to buy?
Mr. Barkley's solution:
Let w = number of packets of welding rods.
100 + 10w < 178
10w < 78
w < 7.8
7.8 rounds to 8.
Solution: Thelma can buy at most 8 packets of welding rods.
Thank You So Much For Your Help!
(this is a repost pls dont ban me jiskha)
This where Barkley went wrong:
14 = 4x – 2 (x – 5)
14 = 4x – 2x – 10
it should be
14 = 4x - 2x + 10
14 = 2x + 10
4 = 2x
2 = x
- 3a < 27
a > -9
Note that change of direction of the inequality when multiplying by a negative value. This is just a shorthand way of moving stuff from one side to the other
- 3a < 27
0 < 27 + 3a
-27 < 3a
-9 < a
dividing by 3 does not change the direction
Let w = number of packets of welding rods.
100 + 10w < 178
This should be
Let w = number of packets of welding rods.
80 + 10w < 178
Now you can finish it off
@Oobleck CAn u help me on mine?
THANK YOU [[So Much]] FOR YOUR HELP!
1. In Mr. Barkley's solution for problem 1, there is an error in the simplification step.
He mistakenly combined like terms and subtracted 10 from both sides of the equation instead of distributing the -2 to both terms within the parentheses correctly.
To solve the problem correctly:
1. Distribute -2 to both terms within the parentheses:
14 = 4x - 2x + 10
2. Combine like terms:
14 = 2x + 10
3. Move 10 to the other side of the equation by subtracting 10 from both sides:
14 - 10 = 2x
4. Simplify:
4 = 2x
5. Divide both sides by 2 to solve for x:
x = 2
Correct solution: x = 2
2. In Mr. Barkley's solution for problem 2, there is an error in the inequality solving step.
He mistakenly divided by -3 and flipped the inequality sign without considering that dividing by a negative number reverses the inequality.
To solve the problem correctly:
1. Start with the given inequality:
7 - 3a < 34
2. Subtract 7 from both sides:
-3a < 34 - 7
-3a < 27
3. Divide both sides by -3, remembering to flip the inequality sign:
a > 27 / -3 (Remember, dividing by a negative flips the sign)
a > -9
Correct solution: a > -9
3. Mr. Barkley's solution for problem 3 is correct. He correctly set up the inequality equation and solved it to find the maximum number of packets of welding rods that can be bought. Therefore, there is no specific error in this solution.
Correct solution: Thelma can buy at most 8 packets of welding rods.