Quote:
Originally Posted by nomadmba
Here are three questions that have left me scratching my head. I have the answers, but not the methodology:
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
2. In the XY plane, at what two points does the graph of y= (x+a)(x+b) intersect the X axis?
1) a + b = 1
2) the graph intersects Y axis at (0, -6)
3. There are 12 temp emloyees in a company. 4 of them will be hired at permanent staff. If 5 of 12 of the temp staff are women, how many of the possible groups of 4 temp employees can consist of 3 women and 1 man?
I know the last should be fairly simple but my mind just doesn't seem to process permutation and combination questions...
Thanks.
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solun for first question, substitute a= b=1 so f(2) = f(1)+f(1)=2f(1) only E satisfies it hence E.
solun for question 2 , clearly the graph intersects x axis at x= -a and x = -b when y = 0
from stm1 1 we dont know what is a and b individually hence we cant find the points on which graph intersect X axis,
from stmt 2 , we know a=0 b =-6 or b=0 or a = -6 so answer should be B