Please help a pleb ASAP

lbr

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Aug 27, 2015
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Hello!

It's the first time I'm posting here and I'm a pretty big pleb at math.



\(\displaystyle 1c.\, \dfrac{\dfrac{4}{5}\, -\, \dfrac{2}{25}}{\dfrac{1}{10}\, -\, \dfrac{3}{5}}\, =\, \dfrac{\dfrac{4}{5}\, \cdot\, \dfrac{10}{10}\, -\, \dfrac{2}{25}\, \cdot\, \dfrac{2}{2}}{\dfrac{1}{10}\, \cdot\, \dfrac{5}{5}\, -\, \dfrac{3}{5}\, \cdot\, \dfrac{10}{10}}\, =\, \dfrac{\dfrac{40}{50}\, -\, \dfrac{4}{50}}{\dfrac{5}{50}\, -\, \dfrac{30}{50}}\)


\(\displaystyle =\, \dfrac{40\, -\, 4}{50}\, \cdot\, \dfrac{50}{5\, -\, 30}\, =\, \dfrac{40\, -\, 4}{5\, -\, 30}\)



\(\displaystyle e. \dfrac{\dfrac{3x}{2}\, -\, \dfrac{15}{4}}{\dfrac{3x}{5}\, +\, \dfrac{3}{2}}\, =\, \dfrac{\dfrac{3x}{2}\, \cdot\, \dfrac{10}{10}\, -\, \dfrac{15}{4}\, \cdot\, \dfrac{5}{5}}{\dfrac{3x}{5}\, \cdot\, \dfrac{4}{4}\, +\, \dfrac{3}{2}\, \cdot\, \dfrac{10}{10}}\, =\, \dfrac{\dfrac{30x}{20}\, -\, \dfrac{75}{20}}{\dfrac{12x}{20}\, +\, \dfrac{30}{20}}\)


\(\displaystyle =\, \dfrac{\dfrac{30x\, -\, 75}{20}}{\dfrac{12x\, -\, 30}{20}}\, =\, \dfrac{30x\, -\, 75}{12x\, -\, 30}\)


\(\displaystyle =\, \dfrac{30x\, -\, 12x}{+75\, -\, 30}\, =\, \dfrac{18x}{35}\)



Could you help me?
 

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fixed typo

Hello!

It's the first time I'm posting here and I'm a pretty big pleb at math.
Could you help me? ...

You do fine until you get down to almost the final steps. However you can not mix parts and pieces from the numerator and denominator as you have done.

In the first problem for example, you are fine down to the
\(\displaystyle \frac{40\, -\, 4}{5\, -\, 30}\)
and then you go astray. From there we have
\(\displaystyle \frac{40\, -\, 4}{5\, -\, 30}\, =\, \frac{36}{-25}\, =\, -\frac{36}{25}\, =\, -1\frac{11}{25}\)
depending on just what your teacher wants for the final answer.

For the second problem, again you are fine down to the
\(\displaystyle \frac{30x\, -\, 75}{12x\, -\, 30}\)
which becomes
\(\displaystyle \frac{30x\, -\, 75}{12x\, -\, 30}\, =\, \frac{15 (2x\, -\, 5)}{6 (2x\, -\, 5)}\, =\, \frac{15}{6}\, =\, \frac{5}{2}\, =\, 2\frac{1}{2}\)
depending on just what your teacher wants for the final answer.
 
Last edited by a moderator:
You do fine until you get down to almost the final steps. However you can not mix parts and pieces from the numerator and denominator as you have done.

In the first problem for example, you are fine down to the
\(\displaystyle \frac{40\, -\, 4}{5\, -\, 30}\)
and then you go astray. From there we have
\(\displaystyle \frac{40\, -\, 4}{5\, -\, 30}\, =\, \frac{36}{-25}\, =\, -\frac{36}{25}\, =\, -1\frac{11}{25}\)
depending on just what your teacher wants for the final answer.

For the second problem, again you are fine down to the
\(\displaystyle \frac{30x\, -\, 75}{12x\, -\, 30}\)
which becomes
\(\displaystyle \frac{30x\, -\, 75}{12x\, -\, 30}\, =\, \frac{15 (2x\, -\, 5)}{6 (2x\, -\, 5)}\, =\, \frac{15}{6}\, =\, \frac{5}{2}\, =\, 2\frac{1}{2}\)
depending on just what your teacher wants for the final answer.

Hooo! Thank you very much! Your help is greatly appreciated! I'll remember to not mix the numerator and denominator. Again, thanks :D
 
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