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Spring98
 one year ago
The work of a student to solve a set of equations is shown:
Equation A: y = 15 – 2z
Equation B: 3y = 3 – 4z
Step 1: –3(y) = –3(15 – 2z) [Equation A is multiplied by –3.]
3y = 3 – 4z [Equation B]
Step 2: –3y = 15 – 2z [Equation A in Step 1 is simplified.]
3y = 3 – 4z [Equation B]
Step 3: 0 = 18 – 6z [Equations in Step 2 are added.]
Step 4: 6z = 18
Step 5: z = 3
In which step did the student first make an error?
Step 4
Step 3
Step 2
Step 1
Spring98
 one year ago
The work of a student to solve a set of equations is shown: Equation A: y = 15 – 2z Equation B: 3y = 3 – 4z Step 1: –3(y) = –3(15 – 2z) [Equation A is multiplied by –3.] 3y = 3 – 4z [Equation B] Step 2: –3y = 15 – 2z [Equation A in Step 1 is simplified.] 3y = 3 – 4z [Equation B] Step 3: 0 = 18 – 6z [Equations in Step 2 are added.] Step 4: 6z = 18 Step 5: z = 3 In which step did the student first make an error? Step 4 Step 3 Step 2 Step 1

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pooja195
 one year ago
Best ResponseYou've already chosen the best response.0Try solving it yourself then see where he made the mistake.

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0HINT: start with substitution

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1i did! is step one wrong?

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0What did he do wrong?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1so step one is the right answer?

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0Well yeah but what was his mistake?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1he put a 3 instead of a 3

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0yea but one thing i dont understand why is there another y?

Hero
 one year ago
Best ResponseYou've already chosen the best response.2Are you sure Step 1 is wrong?

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0\[\huge~–3(y) = –3(15 – 2z)\] it says y equals... 152z...

Hero
 one year ago
Best ResponseYou've already chosen the best response.2Yes but we're allowed to multiply both sides of an equation by 3

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0It says y=152z the person never plugged it in place of y .

Hero
 one year ago
Best ResponseYou've already chosen the best response.2The problem says the student is working to solve the system of equations. There's more than one way to solve a system.

Hero
 one year ago
Best ResponseYou've already chosen the best response.2Multiplying both sides of an equation by 3 does not count as an "error". Nothing "wrong" was done in that step. The student approached differently than you would have.

pooja195
 one year ago
Best ResponseYou've already chosen the best response.0Right but it looks like they used substituion.... :/ This is typed out weirdly ..

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1so witch one would it be?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1plz explain this to me!

Nnesha
 one year ago
Best ResponseYou've already chosen the best response.0y = 15 – 2z 3y = 3 – 4z how would u find the solution ? you need same coefficient but opposite sign to isolate for one variable that's why multiply 1st equation by 3 so 3(y = 15 2z) = ???

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1@Hero is the answer step 4

Hero
 one year ago
Best ResponseYou've already chosen the best response.2Guessing is not the best approach to this. How'd you make it through the other steps successfully? The truth is you wouldn't even really need to ask which step is correct, if you had the correct approach. But I understand you're asking for help. So we know step 1 is correct. What are your thoughts on step 2?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1i don't see anything wrong with step 2

Hero
 one year ago
Best ResponseYou've already chosen the best response.2So the equations in step 1 are equivalent to the equations in step 2? Because when solving systems, for each step, the equations have to all be equivalent.

Hero
 one year ago
Best ResponseYou've already chosen the best response.2In step 1, for the first equation, after multiplying both sides by 3, we have: –3(y) = –3(15 – 2z) In step 2, that equation was supposedly simplified to get: –3(y) = 15 – 2z Tell me, is –3(y) = 15 – 2z equivalent to y = 15 – 2z ?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1becuase its 3y and the other one is plain y

Hero
 one year ago
Best ResponseYou've already chosen the best response.2So what does this observation tell you?

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1that step 2 is wrong. so step two is the answer

Spring98
 one year ago
Best ResponseYou've already chosen the best response.1thanks for explaning.
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