1). x2-4x = 20 2). 2x2 + 8x = 13

ikuti yh..moga membantu. cara nomor 2 jg sama..rumusnya:
Xi,2= -b+_ akar dari D dibgi 2.a
[tex]1)x {}^{2} - 4x - 20 = 0 \\ x 1 = \frac{ - ( - 20) - \sqrt{( - 4) {}^{2} - 4.1.( - 20) } }{2.1} \\ x1 = \frac{20 - \sqrt{16 + 80} }{2} \\ x1 = \frac{20 - \sqrt{96} }{2} \\ x1 = \frac{20 - \sqrt{24 \times 4} }{2} \\ x1 = \frac{20 - 4 \sqrt{6} }{2} \\ x1 = 10 - 2 \sqrt{6} \\ x2 = \frac{20 + 4 \sqrt{6} }{2} \\ x2 = 10 + 2 \sqrt{6} [/tex]