ok wats the domain and range of f(x) = -2x + 3 for x > 1?

Answer 1

Well Richard just look what am doing , hope i can explain for you well

so we have this function f(x) = -2x + 3 for x > 1
when you say x>1 it means your Domain can be all those number which are bigger than 1 , and 1 cant be in the Domain.
So Domain is : (1, the biggest positive number)
if we imagine a=1 and b = the biggest positive number so we would have ;
Domain = (a,b)={ x belongs to R | a < x < b }
Or
x > +1

and now about Range;the first number we can chose is "+2" coz we cant use 1 ,
so if x = +2 : f(x) = (-2)* 2 + 3 = -4 + 3 = 1
if x = +3 ; f(x)= (-2)* 3 +3 = -6 +3 = -3
if x = +4 ; f(x) = (-2)*4 + 3 =-8 +3 = -5
If x = +100 ; f(x) = (-2)*100 +3 = -200 + 3 = - 197

so you see when our " x " or Domains are getting bigger, our " y " or Ranges are getting smaller
well now we have ;
Y or Range = (the smallest NEGATIVE number ,+ 1)
if we imagine a=+1 and b = the smallest negative number so we would have ;

(a,b)={ y belongs to R | b< y < a }
Or
y < +1.

well it's difficult to explain b coz we cant use math signs .but i hope u could understand what i meant.

Answer 2

You need to tell your teacher this is a very stupid question. Mathworld defines domain and range of the above function as follows:

"The term domain is most commonly used to describe the set of values D for which a function (map, transformation, etc.) is defined. For example, a function f(x) that is defined for real values (x element of R) has domain R, and is sometimes said to be "a function over the reals." The set of values to which D is sent by the function is then called the range."

So, the set of all values D is in fact the set of real numbers. The range is also the set of real numbers. You can determine this by sketching the above function - it is a straight line with gradient -2.

If you restrict the domain of x to be greater than 1, then you are also restricting the range to be greater than 1.

The question would have been better phrased as follows:

Given f(x)= -2x + 3, find the domain. What is the range for values of x > 1?

Answer 3

Domain is already given. It is x>1
The range is y<1

The range is less than 1 (NOT greater than 1 like others are saying).
Pick a number greater than 1.
Try 10. Replace x with 10
f(10) = -2(10) + 3
= -20 + 3
- 17
-17 is not greater than 1; therefore, you cannot say that the range is greater than 1.
Try x = 1
f(1) = -2(1) + 3
= -2 + 3
= 1
If you plug in any number greater than one, then f(x) will keep getting smaller and smaller; thus, the range is indeed y < 1.

Answer 4

u 've already said the domain.
x>1
then sub a value for x >1
range: x< or = to - 1

Answer 5

domain is x>1
range is y <1..oops it was wrong b4

Answer 6

f(x) = -2(1) + 3
f(x) = -2 + 3
f(x) = 1

f(x) = -2(2) + 3
f(x) = -4 + 3
f(x) = -1

Range : y < 1
Domain : x > 1

Answer 7

do your own homework so that you'll actually learn it; we won't be available to you when you're taking the test.