# domain and range alevel maths

Announcements
#1
can someone explain to me how do you find the domain and the range from an equation??
0
4 weeks ago
#2
(Original post by lev0701)
can someone explain to me how do you find the domain and the range from an equation??
Have you got an example?
Sometimes you can complete the square to find the minimum value.
Sometimes, if it is a fraction, you can find what the smallest denominator & largest numerator will be, and therefore the maximum.
0
#3
(Original post by booklover1313)
Have you got an example?
Sometimes you can complete the square to find the minimum value.
Sometimes, if it is a fraction, you can find what the smallest denominator & largest numerator will be, and therefore the maximum.
i got this question where f(x)=square root of 1-9x^2 -a<x<a
and i had to find the range to it
the first question was also to find a and i got a=1, and that should be the domain??
0
4 weeks ago
#4
(Original post by lev0701)
i got this question where f(x)=square root of 1-9x^2 -a<x<a
and i had to find the range to it
the first question was also to find a and i got a=1, and that should be the domain??
Yes, the domain is the range of x values, so if a =1, then the domain would be
-1<x<1

For the range, remember that the x squared means that any value below 0 has the same value as the positive value. So I would guess that you would find the range from the minimum x^2 value of 0 and the max value of 1. Then you can work out the range
0
4 weeks ago
#5
(Original post by lev0701)
i got this question where f(x)=square root of 1-9x^2 -a<x<a
and i had to find the range to it
the first question was also to find a and i got a=1, and that should be the domain??
a is not 1.

Domain is the region of x values that the function can be evaluated at.

If a=1 then you’re saying -1<x<1 so you’re saying e.g. x=2/3 is good for the function. But it’s not. Try evaluating square root of 1-9x^2 at x=2/3.
Last edited by RDKGames; 4 weeks ago
0
X

new posts Back
to top
Latest

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### Poll

Join the discussion

#### Does school Maths prepare people well enough for the future?

Yes, it gives everyone a good foundation for any future path (23)
33.33%
Somewhat, if your future involves maths/STEM (31)
44.93%
No, it doesn't teach enough practical life skills (14)
20.29%
Something else (tell us in the thread) (1)
1.45%