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subtracting rational expressions:
7x x2
  
2x 20x+16
please include steps if possible
 2 years ago
 2 years ago
subtracting rational expressions: 7x x2    2x 20x+16 please include steps if possible
 2 years ago
 2 years ago

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moneybirdBest ResponseYou've already chosen the best response.0
\[\frac{7x}{2x}  \frac{x2}{20x+16}\] ?
 2 years ago

PratikBhandariBest ResponseYou've already chosen the best response.2
just take Lcm 2x(20x+16) and solve in as usual way
 2 years ago

moneybirdBest ResponseYou've already chosen the best response.0
\[\frac{7}{2}  \frac{x2}{4(5x+4)}\]
 2 years ago

moneybirdBest ResponseYou've already chosen the best response.0
multiply 2(5x+4) both top and bottom of fraction 7/2
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
Reduce the first fraction to 7/2. Now the common denominator is 2(10x+8) When you rewrite the first fraction with that denominator, it becomes 7(10x+8)/2(10x+8). since the second fraction already has that denominator, it does not change so now the problem is (70x+56x+2)/2(10x+8) or (69x+58)/2(10x+8)
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
why 2(5x+4) and not 4(5x+4)?why 2(5x+4) and not 4(5x+4)?
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
why 2(5x+4) and not 4(5x+4)?
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
when i factor 20x+16 I get 4(5x+4)
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
why do you multiply times 2(5x+4) anmd not 4(5x+4)?
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
Because the first fraction has a denominator of two. So rewrite the denominator of the second fraction as 2(10x+8). Now ask yourself: By what should I multiply the first denominator which is 2 to get the second denominator which is 2(10x+8)? Isn't it clear that the answer is "multiply by (10x+8)"? Then do the same thing to the numerator.
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
how di you get 2(10x+8)?
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
I took the denominator of the second fraction which is 20x + 16 and factored out a 2 . Since 20x+16 = 2(10x+8) they are equivalent
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
you're just trying to make it equal to the other denomitaor?
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
The reason I factored out the two is because the denominator of the first fraction is 2 and I wanted to see what I should multiply the first fraction by to get the same denominator the second fraction has.
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
or it always hast to be the lcm?
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
or it always hast to be the lcm?
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
Yes, love. You cannot subtract two fractions unless they have the same denominator.
 2 years ago

neverforgetvivisteeBest ResponseYou've already chosen the best response.0
but i mean you divide it to the lcm or just to make it equal to the other fraction?
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
It is most efficient if the denominator is the LCM of both denominators but not mandatory. If the denominators are the same then the fractions can be subtracted.
 2 years ago

MertsjBest ResponseYou've already chosen the best response.0
You can see that 20x+16 is the LCM of 2 and 20x+16. I only wrote 20x+16 as 2(10x+8) to make it clear that 20x+16 IS the LCM
 2 years ago
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