Question

22) 4 + x (x - 4) = x
(R: 1,4)​

Answer 1

$4 + {x}^{2} - 4x = x \\ {x}^{2} - 4x - x + 4 = 0 \\ {x}^{2} - 5x + 4 = 0 \\ a = 1 \\ b = - 5 \\ c = 4 \\ x = \frac{ - b + - \sqrt{ {b}^{2} - 4 \times a \times c } }{2 \times a} \\ x = \frac{ - ( - 5) + - \sqrt{ {( - 5)}^{2} - 4 \times 1 \times 4 } }{2 \times 1} \\ x = \frac{5 + - \sqrt{25 - 16} }{2} \\ x = \frac{5 + - \sqrt{9} }{2} \\ x = \frac{5 + - 3}{2} \\ x1 = \frac{5 + 3}{2} = \frac{8}{2} = 4 \\ x2 = \frac{5 - 3}{2} = \frac{2}{2} = 1$