You isolate one variable. Let's say that x will be that variable in the first equation: x-y=1 +y +y x=y+1 So now you have the equation for x. All you have to do is substitute it into the other: x=y+1 (y+1)+y=3 Combine like terms and solve: 2y+1=3 -1 -1 2y=2 2y/2=2/2 y=1 Now that you have the value of one, substitute it into either of the equations to find x. If you put it in the first: x-1=1 +1 +1 x=2 If you put it into the other, you would get the same answer. Therefore, y=1 and x=2
No such thing as a vertex of a graph... Eliminate B and C. Try f(3) = 4(3-5)(3+3) is not zero eliminate A. So answer must be D. Check: f(-3) has factor -3+3 = 0. f(5) has factor 5-5 = 0.
