Method I

(x - $\frac{3}{4}$)(x - (-4)) = 0

Note: -- = + or -(-) = +

(x - $\frac{3}{4}$)(x + 4) = 0

x(x + 4) -$\frac{3}{4}$(x + 4) = 0

x² + 4x -$\frac{\mathrm{3x}}{4}$ - $\frac{3}{4}$ x 4 = 0

x² + 4x -$\frac{\mathrm{3x}}{4}$ - 3 = 0

Get rid of the fraction by multiplying both sides by the denominator 4

4 x x² + 4 x 4x -$\frac{\mathrm{3x}}{4}$ x 4 - 3 x 4 = 0 x 4

4x² + 16x - 3x - 12 = 0

4x² + 13x - 12 = 0

Method II

Sum of roots = $\frac{3}{4}$ + -4

Sum of roots = $\frac{3}{4}$ - 4 = $\frac{\mathrm{1\; x\; 3\; -\; 4\; x\; 4}}{4}$ = $\frac{\mathrm{3\; -\; 16}}{4}$ = -$\frac{13}{4}$

Product of roots = -4 x $\frac{3}{4}$ = -3

x² - (-$\frac{13}{4}$)x + -3 = 0

x² + $\frac{13}{4}$x - 3 = 0

Get rid of the fraction by multiplying both sides by the denominator 4

4 x x² + 4 x $\frac{13}{4}$x - 3 x 4 = 0 x 4

4x² + 13x - 12 = 0