Solve by Cross Multiplying

[gamingwithnoob]

Sir you should start a series of solving complicated or Olympiad problems

[JohnDoe-spdc]

I really love these short form lessons. It really helps me stay up on my math skills. When I watch you go through the process, everything I forgot comes to the front of my mind. Thank you!

[Martinsim]

We can Also compare nominator an dominator to get m=1 and 3m-n=5
By substituting 1 as m and solving for n=-2
we get -2/1 = -2

[CChronicles_FF]

In Russia we call it cross-examination))) And usually we learn that like when we are 10-11 y.o.

[nda]

But we also have to keep the condition in mind that 3m-n>0 to do cross multipilaction which will give n/m<3 which here is coincidentally satisfied with the answer.

[Ghost_]

6:31 from now onwards I will never forget to like your videos mam 😂😅

[hmmm_pizza]

It's a pretty cute answer to a seemingly complicated and boring problem

[oddlyspecificmath]

Sometimes we just want to know what relationship two unknowns have; perhaps sometimes they're expensive to calculate, or they're functions outputting another function, etc.

[Ghost_]

Wow I didn't know that 100 mins = 176 mins 😂😅
BTW amazing session mam, keep growing 🎉

[engjayah]

Much easier if you divide both numerator and denominator by m and say k=n/m
Then 5/(3-k) = 1 and k= -2

[not_vinkami]

Another way is to abuse fractions as a type of matrix and declare that m=1 and 3m-n=5. Solving it gives n=-2 and the problem is easily solved.

And if you care, use k and 5k instead of 1 and 5 for a rigorous proof

[joelllamocuro.]

M=1 and 3M-N=5

3(1)-N=5
-N=2
N=-2

N/M= -2/1 =-2

[kaivalya]

You cant actually directly cross multiply, correct me if am wrong but i think you are first supposed to assume that denominator is not equal to zero and then solve. After that if solution makes it to be zero, it is deemed incorrect. Here luckily that was the case.

[Rofida-rhwq]

We can say that m= 1
And 3m-n = 5
and just solve it

[rangaswamyks]

m=1
3m-n=5
3-n=5
n=-2
so( n/m) =-2/1=-2

[anupmaupadhyay]

I done it by comparing
m=1
And 3m-n= 5 put m=1 then u will get
n=-2 then
n/m= -2

[Sobioytccc]

Why I am not comfortable with cross multiply, is it the mere name 😊

[jakehobrath]

Couldn’t you just say m=1, and 3m-n=5, then make n=3m-5, n=3-5, n=-2?

[sifdlwe]

This is not a very good solution to this problem. Wouldn't the following solution be sufficient:
m/(3m-n)=1/5 ⇒(3m-n)/ｍ=5 ⇒3-ｎ/ｍ=5 ⇒-n/m=2 ⇒ｎ/ｍ=-2 ?

[dakoz]

m/(3m-n) = 1/(3 - n/m) = 1/5 => 3 - n/m = 5 => n/m = 3 - 5 = -2