While Desmos is the only graphing calculator tool allowed for use on the SAT, the Ti-84 Plus CE is the best of many calculator option for the ACT. “Y1Y2” is one the most helpful “cool calculator tricks” the Ti-84 Plus CE can perform, leveraging raw computing power to solve equations by graphing.
To solve any equation on the ACT using the Ti-84 Plus CE:
1. Set Y1 equal to the left side of the given equation to be solved, and Y2 equal to the right side.
2. Hit the graph button, and make sure both graphs appear in the viewing window.
3. Note the coordinates of the points of intersection. The x-coordinate(s) will be the given equation's real solution(s).
It can sometimes be hard to finagle the graphs of Y1 and Y2 so that both show up in the same viewing window, however.
In that case, carry out the following steps to make viewing both graphs easier,:
It can sometimes be hard to finagle the graphs of Y1 and Y2 so that both show up in the same viewing window, however.
In that case, carry out the following steps to make viewing both graphs easier,:
1. Remember that since Y1= Y2, Y1–Y2 = 0.
2. Set Y3 equal to Y1–Y2, turn off Y1 and Y2, and graph Y3 alone.
4. Real solutions to the original equation will be zeros of Y3. These solutions should now conveniently appear as x-intercepts (adjustment of window variables Xmin and Xmax may be necessary to show both zeros).
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