PSAT #2, Section 4, #29

I’d get this one by substituting. Since both equations are given to you in *y* = notation, set them equal to each other.

That tells you that *x* is either 1 or 4, so pick one and solve for what *y* must be in that case. Use the second equation because it’s simpler! For example, if *x* = 1, then the second equation tells you that *y* = 1 – 1 = 0. So in that case, the product of *x* and *y* is (1)(0) = 0.

The other possibility is that *x* = 4 and *y* = 3. In that case, the product of *x* and *y* would be (4)(3) = 12.

Note that although my first instinct here was to solve algebraically, this is also a good one to use your graphing calculator (if you have one). Just graph both equations, find either of the intersections, and multiply their coordinates to find the product of *x *and *y*.