Question

$frac{18-6x^{2} }{5-x} и frac{x^{2}-15x }{5-x}$
при каких значениях х значения данной дроби равны

Answer 1

$frac{18-6x^{2} }{5-x} = frac{x^{2}-15x }{5-x} \ frac{18-6x^{2} }{5-x} - frac{x^{2}-15x }{5-x}=0 \ frac{18-6x^{2}- x^{2} +15x }{5-x}=0 \ frac{-7x^{2} +15x+18 }{5-x}=0 \ left { {{{-7x^{2} +15x+18=0} atop {5-x neq 0}} right.$
$left { {{{-7x^{2} +15x+18=0} atop {x neq 5}} right. \ \ -7x^{2} +15x+18=0 \ D=15^{2}-4*(-7)*18=225+504=729=27^{2} \ x_{1}= frac{-15+ sqrt{729} }{2*(-7)} = frac{-15+27}{-14} = frac{12}{-14} = - frac{6}{7} \ x_{2}= frac{-15- sqrt{729} }{2*(-7)} = frac{-15- 27}{-14} = frac{-42}{-14} =3$

x=3
x=-6/7
x не равно 5