# question refers to class 11th maths..chapter Limits and derivatives......We have to find the limt of this qustion....Lim(x-0) (x+1)^5 - 1 / x . I got solution to this qustion on topperlearnign bu i have doubt....Solution Says - Put x+1 = y so that y -> as x - 0[my question is why do they put x+1 = y ] lim(x-0) (x+1)^5 - 1 / x = lim(y-1) y^5 -1 / y-1 lim(y-1) y^5-1^5 / y-1 5.1 ^ 5-1 =5

2
by girijanair2010

• man
• Ambitious
2014-01-29T09:31:14+05:30
If you put x=y in the given equation it would make no change to the equation as y will take place of x only, Thus what you get will be
which is same as your given  equation.
For finding a solution to any question the logic is to convert the question into general (predefined forms) which we have already learned.
The asked limit looks alot similar to the formula :

So, for converting the above format in this predefined format we put x+1=y
Now
So we can write,

Here a=1, n=5 so the solution is  = 5
2014-01-29T17:18:06+05:30
It is common sense that to solve the limits you have to convert the question to a known form which you can solve. to do exactly that you have to do the operation that has been suggested.