Hi there,
I don't understand anything to this PS. Could you explain the concept (simple way)?
For which of the following functions is f(a+b) = f(a)+f(b) for all positive numbers "a" and "b" ?
a) f(x)=x²
b) f(x)= x+1
c) f(x)= (root) x
d) f(x)= 2/x
e) f(x)= -3x
function
This topic has expert replies
if you are stumped at questions with variables in answer choices, the golden rule is PLUG in for the variables
for the question above , say a =1 , b=1
substitute above values in the question stem :
f(2) = 2f(1)
now substitute the values of a and b in the answer choices and see which one satisfies f(2) = 2f(1)
only E does, hence it is the answer!
hope it helps..
for the question above , say a =1 , b=1
substitute above values in the question stem :
f(2) = 2f(1)
now substitute the values of a and b in the answer choices and see which one satisfies f(2) = 2f(1)
only E does, hence it is the answer!
hope it helps..
-
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Replace x with addition of two numbers.
For example x = 4 + 3,
Then substitute a=4 and b=3
Do it for all options
(E) is the answer
f(x)= -3(x)
= -3(4+3)
= -21
And f(x) = -3(4) + (-3(3))
= -12 - 9
=-21
For example x = 4 + 3,
Then substitute a=4 and b=3
Do it for all options
(E) is the answer
f(x)= -3(x)
= -3(4+3)
= -21
And f(x) = -3(4) + (-3(3))
= -12 - 9
=-21
-
- Master | Next Rank: 500 Posts
- Posts: 103
- Joined: Fri May 22, 2009 3:56 am
- Thanked: 4 times
- GMAT Score:470
Replace x with addition of two numbers.
For example x = 4 + 3,
Then substitute a=4 and b=3
Do it for all options
(E) is the answer
f(x)= -3(x)
= -3(4+3)
= -21
And f(x) = -3(4) + (-3(3))
= -12 - 9
=-21
For example x = 4 + 3,
Then substitute a=4 and b=3
Do it for all options
(E) is the answer
f(x)= -3(x)
= -3(4+3)
= -21
And f(x) = -3(4) + (-3(3))
= -12 - 9
=-21