Basic solving for variable question.

[davie08]

Homework Statement

if (4x+1) + 6 = 9, then x=?

Homework Equations

The Attempt at a Solution

the answer is -1 and 1/2, but how could -1 work wouldn't that make the answer 3 instead of 9.

 

[Mark44]

Homework Statement

if (4x+1) + 6 = 9, then x=?

Homework Equations

The Attempt at a Solution

the answer is -1 and 1/2, but how could -1 work wouldn't that make the answer 3 instead of 9.

The equation is linear, so there can be only one solution (x = 1/2). Are you sure you have written the equation correctly?

 

[davie08]

I meant to say 1/2 or -1 but I feel like they screwed up its a sample placement test with my university.

 

[Mark44]

The only solution to the equation you gave is x = 1/2.

 

[davie08]

okay thanks I've never had a question answered so fast in a forum before, I was trying out this forum compared to another one but this forum wins hands down lol.

 

[eumyang]

Homework Statement

if (4x+1) + 6 = 9, then x=?

...

the answer is -1 and 1/2, but how could -1 work wouldn't that make the answer 3 instead of 9.

I still think there's a possibility that you didn't copy the question right. If there were absolute value symbols instead of parentheses:
|4x+1| + 6 = 9
... then there would indeed be two solutions, -1 and 1/2.

 

[Mark44]

I still think there's a possibility that you didn't copy the question right. If there were absolute value symbols instead of parentheses:
|4x+1| + 6 = 9
... then there would indeed be two solutions, -1 and 1/2.

I'll bet that's it. My thought was that there might be an exponent missing, but that didn't work out.

 

[HallsofIvy]

I still think there's a possibility that you didn't copy the question right. If there were absolute value symbols instead of parentheses:
|4x+1| + 6 = 9
... then there would indeed be two solutions, -1 and 1/2.

The other possibility is that some fool, who typed up the exam, replaced "|" with "(" and ")"!

 

[shiva999]

answer is only 1/2,and i don't know how you got -1.

 

[HallsofIvy]

answer is only 1/2,and i don't know how you got -1.

Did you not read the other replies? The problem is, almost certainly, to solve
|4x+ 1|+ 6= 9, not (4x+ 1)+ 6= 9.

 

[Ray Vickson]

Did you not read the other replies? The problem is, almost certainly, to solve
|4x+ 1|+ 6= 9, not (4x+ 1)+ 6= 9.

Either that, or the questioner wrote "and" instead of "or" in a multiple-choice setting (or the OP copied the question incorrectly).

RGV