Question

-0.4z - 3/ 1.5z +9 = -7/ 5​

Answer 1

Step-by-step explanation:

$\bf -0,4z - \frac{3}{1,5z} + 9 = \frac{-7}{5}$

$\bf -0,4z - \frac{3}{1,5z} + 9 = \frac{-7}{5}, z ≠ 0$

$\bf -\frac{2}{5}z - \frac{3}{\frac{3}{2}z} + 9 = -\frac{7}{5}$

$\bf -\frac{2}{5}z - \frac{3}{\frac{3z}{2}} + 9 = -\frac{7}{5}$

$\bf -\frac{2}{5}z - \frac{2}{z} + 9 = -\frac{7}{5}$

$\bf -\frac{2}{5}z - \frac{2}{z} + 9 + \frac{7}{5} = 0$

$\bf -\frac{2}{5}z - \frac{2}{z} + \frac{52}{5} = 0$

$\bf \frac{-2z²-10+52z}{5z} = 0$

$\bf -2z²-10+52z=0$

$\bf -2z²+52z-10=0$

$\bf z²-26z+5=0$

$\bf z = \frac{-(-26)±\sqrt{(-26)²-4×1×5}}{2×1}$

$\bf z = \frac{26±\sqrt{676-20}}{2}$

$\bf z = \frac{26±\sqrt{656}}{2}$

$\bf z = \frac{26±4\sqrt{41}}{2}$

$\bf z = \frac{26+4\sqrt{41}}{2}$

$\bf z = \frac{26-4\sqrt{41}}{2}$

$\bf z1 = 13+2\sqrt{41}$

$\bf z2 = 13-2\sqrt{41}$