Solving first and second degree equations

  • Thread starter late347
  • Start date
  • #1
301
15

Homework Statement



solve the equations below


1.) 2x -1 = (1/2) *x +3

and

2) 1/x - 4/ x2= 0

Homework Equations


3. The Attempt at a Solution [/B]


2x -1 = 0,5x +3

2x= 0,5x +4
1,5x = 4
x= 4/ 1,5
x= 8/3

my math teacher told me that the x= 8/6 would have been correct solution to this first one



1/x -4/ x2 = 0

1/x = 4/x2

we enlarge the fraction 1/x

x/ x2 = 4/ x2

multiply both sides by x2

x= 4

singular solution assuming that originally x is unequal to 0 (because cannot divide with 0)

my teacher told me that this latter equation has twin solutions either x=-4 or x= 4

plugging -4 into the original equation, this seems not true at all...

-0,25 -( 0,25) = 0

-0,5 = 0

untrue.
 

Answers and Replies

  • #2
ehild
Homework Helper
15,543
1,912

Homework Statement



solve the equations below


1.) 2x -1 = (1/2) *x +3

and

2) 1/x - 4/ x2= 0

Homework Equations


3. The Attempt at a Solution [/B]


2x -1 = 0,5x +3

2x= 0,5x +4
1,5x = 4
x= 4/ 1,5
x= 8/3

my math teacher told me that the x= 8/6 would have been correct solution to this first one



1/x -4/ x2 = 0

1/x = 4/x2

we enlarge the fraction 1/x

x/ x2 = 4/ x2

multiply both sides by x2

x= 4

singular solution assuming that originally x is unequal to 0 (because cannot divide with 0)

my teacher told me that this latter equation has twin solutions either x=-4 or x= 4

plugging -4 into the original equation, this seems not true at all...

-0,25 -( 0,25) = 0

-0,5 = 0

untrue.
Your solutions are correct.
 
  • #3
301
15
Your solutions are correct.

Thank you for prompt response. It looks like even math teachers make silly mistakes sometimes. Twice in this problem sheet.

Can you take a gander at my other thread about algebra problem that I had. I just posted a simple word problem in the same precalculus homework math subrofum
 
  • #4
ehild
Homework Helper
15,543
1,912
Thank you for prompt response. It looks like even math teachers make silly mistakes sometimes. Twice in this problem sheet.

Can you take a gander at my other thread about algebra problem that I had. I just posted a simple word problem in the same precalculus homework math subrofum
I see you solved it.
 
  • #5
SteamKing
Staff Emeritus
Science Advisor
Homework Helper
12,796
1,670
Time to find another math teacher. :sorry: :rolleyes: :mad:
 

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