Solve ##\dfrac{3x-6}{5-x}+\dfrac{11-2x}{10-4x}=3\dfrac{1}{2}##

  • Thread starter RChristenk
  • Start date
  • Tags
    Precalculus
  • #1
RChristenk
46
4
Homework Statement
Solve ##\dfrac{3x-6}{5-x}+\dfrac{11-2x}{10-4x}=3\dfrac{1}{2}##
Relevant Equations
Algebraic manipulation
I've multiplied everything out on paper and got ##x=2, \dfrac{15}{4}##, which is correct. However multiplying directly is tedious and from observing this problem I suspect there is a simplification or trick that I missed.

##3\cdot\dfrac{x-2}{5-x}+\dfrac{1}{2}\cdot\dfrac{11-2x}{5-2x}=\dfrac{7}{2}##

Multiply both sides by ##2##:

##\dfrac{6(x-2)}{5-x}+\dfrac{11-2x}{5-2x}=7##

And then I'm stuck. But the denominators ##5-x, 5-2x## are tantalizingly close to each other, but I just can't figure out how to simplify/substitute/manipulate it to process this problem. Besides just multiplying it out of course.
 
Physics news on Phys.org
  • #2
I don't see a way to simplify things. The best you could do is:
$$6(x-2)(5-2x) + (11-2x)(5-x) = 7(5-x)(5-2x)$$$$6(x-2)(5-2x) + (5-x)(11-2x - 35 + 14x) = 0$$$$6(x-2)(5-2x) + (5-x)(12x-24) = 0$$$$6(x-2)(5-2x) +6(x-2)(10 - 2x) = 0$$$$6(x-2)(15 - 4x) = 0$$
 
  • Like
Likes MatinSAR, chwala, SammyS and 2 others
  • #3
[tex]
-3-\frac{9}{x-5}+\frac{1}{2}-\frac{3}{2x-5}=3+\frac{1}{2}[/tex]
[tex]\frac{3}{x-5}+\frac{1}{2x-5}=-2[/tex]
[tex]4x^2-23x+30=0[/tex]
[tex](x-2)(4x-15)=0[/tex]
 
Last edited:
  • Like
Likes MatinSAR, chwala, RChristenk and 1 other person
  • #4
RChristenk said:
Homework Statement: Solve ##\dfrac{3x-6}{5-x}+\dfrac{11-2x}{10-4x}=3\dfrac{1}{2}##
Relevant Equations: Algebraic manipulation

I've multiplied everything out on paper and got ##x=2, \dfrac{15}{4}##, which is correct. However multiplying directly is tedious and from observing this problem I suspect there is a simplification or trick that I missed.

##3\cdot\dfrac{x-2}{5-x}+\dfrac{1}{2}\cdot\dfrac{11-2x}{5-2x}=\dfrac{7}{2}##

Multiply both sides by ##2##:

##\dfrac{6(x-2)}{5-x}+\dfrac{11-2x}{5-2x}=7##

And then I'm stuck. But the denominators ##5-x, 5-2x## are tantalizingly close to each other, but I just can't figure out how to simplify/substitute/manipulate it to process this problem. Besides just multiplying it out of course.
Here is my two cents.
I much prefer methodical approaches that use basic principles to reliably solve the vast majority of problems. I don't really care if they require a little more work. If you look for cute and clever tricks, you might learn a million of them and still not have a basic understanding.
 
  • Like
Likes MatinSAR, chwala, docnet and 2 others

Similar threads

  • Precalculus Mathematics Homework Help
Replies
8
Views
291
  • Precalculus Mathematics Homework Help
Replies
2
Views
877
  • General Math
Replies
1
Views
664
  • Precalculus Mathematics Homework Help
Replies
3
Views
2K
Replies
3
Views
724
Replies
1
Views
904
  • Precalculus Mathematics Homework Help
Replies
1
Views
880
  • Precalculus Mathematics Homework Help
Replies
7
Views
758
  • Calculus and Beyond Homework Help
Replies
2
Views
599
  • Precalculus Mathematics Homework Help
Replies
2
Views
1K
Back
Top