Finding Domains

Hey guys, can one of you help me with these two problems. I have tried several times to solve it on my own and I just don't understand.


Find the domain of x- 2y=1if the range is {-2, 0, 5, 8}

Solve Y= -2X + 7 if the domain is { -2, 0, 4, 7}


How do I do these problems?

Dominic said:

Find the domain of x- 2y=1if the range is {-2, 0, 5, 8}

Click to expand...

If you have the Domain, you could solve for 'y' and just plug things in for 'x' and find the Range. Since you have the Range, solve for 'x' and plug things in for 'y' to find the Domain.

x - 2y = 1
x = 1 + 2*y
1 + 2*(-2) = 1 - 4 = -3 <== There's your first Domain element.

It's a piece of cake if your function (solved for 'y') has an inverse function (solved for 'x').