How do you find the domain for these?

Question

1.) y = -2 / x+1

2.) y = 6 / x-3

Answer 1

a domain is a set of number x that will define y...

there are only two things to look out if you are looking for the domain...

one are radicals and two are denominators...

if x is inside a radical expression, x, or the entire expression in side the radical, must be greater that or equal to zero...

if x is in the denominator, it must not be equal to zero... so equate x, or the entire denominator, with zero...

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now, answering your question...

1. y = -2/x+1

x+1 = 0

x = -1

domain: all real numbers except -1

2. y = 6/x-3

x-3 = 0

x = 3

domain: all real numbers except 3

Answer 2

you can't divide by a 0.

1) x can't be -1

so domain: {x l x ≠ -1}

2) x can't be 3

domain : {x l x ≠ 3}

Answer 3

The domain of a function is the set of values for x such that the expression for y is defined.  In these cases, the doman will be any value for x such that the denominator of the fraction is not equal to zero, because a rational expression is undefined when its denominator equals zero.

1) For y = -2 / (x + 1), the domain is all real numbers except for -1, i.e., x != -1, because x = -1 would give you y = -2 / (-1 + 1) = -2 / 0, which is undefined.

2) By similar logic, the domain is x != 3.

(!= means "is not equal to.")