(6-x) / (5-x) + 7 = 9x / 4 D = ℝ \ { 5 }
Der HN ist 4 * (5-x)
Gleichung * HN ( die Einzelnenner kürzen sich weg)
(6-x) * 4 + 7 * 4 * (5-x) = 9x * (5-x)
164 - 32x = 45x - 9x2 | + 9x2 | -45x
9x2 - 77x + 164 = 0 | : 9
x2 - 77/9 x + 164/9 = 0
x2 + px + q = 0
pq-Formel: p = - 77/9 ; q = 164/9
x1,2 = - p/2 ± \(\sqrt{(p/2)^2 - q}\)
= 77/18 ± \(\sqrt{5929/324 - 5904/324 }\) = 77/18 ± \(\sqrt{25/324}\)
= 77/18 ± 5/18
x1 = 82/18 = 41/9 ; x2 = 72/18 = 4 (beide in D)