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You will find that numerous exercises in this lab manual will require you to determine the relationship between two variables. This section includes graphs of common proportions that you may encounter in these exercises.

$y\propto x$ ($x$ and $y$ are directly proportional), which is a linear relationship $ y = mx + b$.

Figure 1:yxy\propto x (xx and yy are directly proportional), which is a linear relationship y=mx+b y = mx + b.

$y \propto x^2$, which follows the equation $y = a x^2 + bx + c$

Figure 2:yx2y \propto x^2, which follows the equation y=ax2+bx+cy = a x^2 + bx + c

$y \propto x^3$, which follows the equation $y = a x^3 + bx^2 + cx + d$

Figure 3:yx3y \propto x^3, which follows the equation y=ax3+bx2+cx+dy = a x^3 + bx^2 + cx + d

inversely proportional to x, or $y \propto 1/x$.

Figure 4:inversely proportional to xx, or y1/xy \propto 1/x.

inversely proportional to $x^2$, or $y \propto 1/x^2$.

Figure 5:inversely proportional to x2x^2, or y1/x2y \propto 1/x^2.

proportional to the square root of $x$ or $y \propto \sqrt{x}$.

Figure 6:proportional to the square root of xx or yxy \propto \sqrt{x}.

proportional to the reciprocal of the square root of $x$ or $y \propto 1/\sqrt{x}$.

Figure 7:proportional to the reciprocal of the square root of xx or y1/xy \propto 1/\sqrt{x}.