Question

$frac{18}{x} - frac{18}{9-x} = frac{9}{10}$

Answer 1

ОДЗ
10x(9-x)≠0⇒x≠0 U x≠9
18*10(9-x)-18*10x=9x*(9-x)
1620-180x-180x-81x+9x²=0
9x²-441x+1620=0
x²-49x+180=0
x1+x2=49 U x1*x2=180
x1=4 U x2=45