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functions

by hpgmat » Fri Nov 13, 2009 9:48 pm
for which of following functions is f(a+b) = f(a) + f(b) for all positive numbers a and b

A) f(x) = x squared
B) f(x)= x+1
C) f(x)= square root of x
D) f(x)= 2/x
E) f(x)= -3x

please show calcs
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by xcusemeplz2009 » Fri Nov 13, 2009 9:54 pm
1)f(x)=x^2
f(a+b)=(a+b)^2
f(a)=a^2
f((b)=b^2
hence (a+b)^2#a^2+b^2

likewise solve u will get E as the ans for which LHS ans RHS are equally...
its all mental calculation....
E)
f(a+b)=-3(a+b)
fa=-3a
fb=-3b
fa+fb=-3(a+b)
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