adkikani wrote:
niks18 pikolo2510 pushpitkcQuote:
x+y = x-y
Hence y =0
We could perform subtraction of x from both sides of equality even though
we do not know sign of x since we are dealing with
equality and
subtraction / addition. We
can not perform same step in case of inequality and division. Am I correct?
Hi
adkikaniyou can perform addition and subtraction with inequalities as well even if you don't know the value of the variable, provided the sign of inequality is SAME.
for e.g if x>y and a>b, then you can add them as x+a>y+b. but you cannot subtract the second inequality from the first because on subtracting the second inequality changes its sign as -a<-b.
but if you had x>y and d<e, then second inequality can be subtracted because in that case sign of both inequality will be same. x>y & -d>-e now add them to get
=>x-d>y-e
However you cannot multiply or divide the inequalities without knowing the value of the variable i.e. whether they are positive or negative.