b)√(x^2+9) = √(x^2+3^2) (this is not formula,9 = 3^2

we cannot simplify it further to modulus of x + 3

c) (7+a)/7 = 7/7 + a/7

= 1 + a/7

d) x/ x+y

we cannot split this denominator terms separately like numerator

that is ,we cannot write this into x/x + x/y( as we done in the above problem,in the above problem we had separated the numerator terms which is allowed,but this is not the case with denominator)

Aug 30th, 2015

e) sin x= 2 sin (x/2 )cos (x/2)

this is a basic formula ,so it is true

f) 2/ (4+x)

this is similar case of question d

we cannot separate denominator terms into 2/4 + 2/ x = 1/2 + 2/x

so this solution is false

g)e^ ln x = x

that is e^ ln ( of any number) = that number

here e^ ln 5/2 = 5/2

so it is true

Aug 30th, 2015

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