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1. For which of the following functions is f(a+b)= f(a) + f(b) for all positive numbers a and b?
a. f(x) = x*x
b. f(x) = x + 1
c. f(x) = sq. root of x
d. f(x) = 2/x
e. f(x) = -3x
replace a, b and a+b in these equations.. you can do it mentally.
the answer is E..
a. (a+b)*(a+b) = a*a + b*b (false)
b. a + b + 1 = a + 1 + b + 1 (false)
c. sqrt(a+b) = sqrt(a) + sqrt(b) [false]
d. 2/(a+b) = 2/a + 2/b (false)
e. -3(a+b) = -3a - 3b (TRUE)
IMO E
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