akpareek wrote:The function f is defined by f(x)= √x-10 for all positive numbers x. If u= f(t) for some positive numbers t and u. What is it terms of u?
A. √(u+10)
B. √(u+10)2
C. √(u+10)
D. (u+10)2
E. (u2+10)2
Dear
Akpareek,
I'm happy to respond.
I want to explain, you have made a couple mistakes in posting the question that make it absolutely unanswerable. Understanding these mistakes in detail will advance you mathematical understanding.
The first is that when a number of term is under the "roof" of a radical sign, that constitutes a grouping symbol. See:
https://magoosh.com/gmat/2013/gmat-quant ... g-symbols/
By contrast, the rtf symbol "√" is not a grouping symbol, and we have to use parentheses to denote the proper grouping. You wrote:
f(x)= √x-10
which could mean
(a)
f(x)= √(x) - 10
or
(b)
f(x)= √(x-10)
I suspect you mean the latter, but without the parentheses, what you have written is mathematically ambiguous. There's actually quite a bit of deep mathematics behind the idea of grouping symbols.
Another mistake concern exponents. When we write, say, x-squared in rtf, we need to use the carot symbol, ^, which is shift-6 on any QWERTY keyboard. Thus, x-squared is written
x^2.
The most serious problem concerns the question as you have written it:
What is it terms of u?
The word "
it" has no clear referent. This may simply be a typo --- did you mean:
What is t terms of u?
Now, I will assume the function is:
f(x)= √(x-10), so
u = √(t-10)
and I will assume the question is:
What is t terms of u?
If
u = √(t-10)
then
u^2 = t-10
and
u^2 + 10 = t
This does not appear among the answer choices. Apparently, given the ambiguity, I guessed incorrectly. I could get again, but I think it's best if you consult the source and resolve all ambiguities.
Does this make sense?
Mike
