help required!!!!!! @_@

[8dltndus]

hi i have a problem that i thought that i knew it but i got it wrong.
so the problem is
1)without graphing, tell whether each point is on the graph of 2x-y=5:{1,-2}

and what i did is i substituted the numbers so the equation became,2(1)-(-2)=5, which then changes to 2+2 which is not 5, and i wan't really sure if that was how i solve these kinds of problem.so plese help and tell me what I did wrong.
thank you.

 

[Mrspi]

hi i have a problem that i thought that i knew it but i got it wrong.
so the problem is
1)without graphing, tell whether each point is on the graph of 2x-y=5:{1,-2}

and what i did is i substituted the numbers so the equation became,2(1)-(-2)=5, which then changes to 2+2 which is not 5, and i wan't really sure if that was how i solve these kinds of problem.so plese help and tell me what I did wrong.
thank you.

If a point DOES lie on the graph of a particular equation, then that equation must be TRUE when you replace "x" and "y" in the equation with the coordinates of the point you're wondering about.

Your point is (1, -2).

When you substituted 1 for x, and -2 for y, and did the arithmetic, you got 4 = 5, which is not true. So, the point (1, -2) is NOT on the graph of the equation 2x - y = 5.

I hope this helps you.

 

[8dltndus]

but the answer key says that it's a yes. so is the answer key wrong?

 

[pka]

but the answer key says that it's a yes. so is the answer key wrong?

YES the text's answer is wrong.

 

[8dltndus]

thanks