Question

Решите уравнения 4х^{2}-5х=0:
$frac{4}{5} x^{2} -45=0$
5x^{2} +7х+4=0

Answer 1

$frac{4}{5}x^2-45=0; |cdot 5\\4x^2-225=0\\(2x-15)(2x+15)=0\\x_1=frac{15}{2}=7,5; ;; x_2=-frac{15}{2}=-7,5\\\5x^2+7x+4=0\\D=49-80=-31 textless 0; ; Rightarrow ; ; xin varnothing$