A)(3a+1/3b)^2
b)(0.5m)^2+(5.3n)^2=0.25m+28.09n
v)(0.6x)^2*(9y)^2
X^2-x-30=0
По теореме Виета:
X1+X2=-b/a
X1*X2=c/a
Находим:
X1+X2= 1
X1*X2=-30
Значит, X1= -5; X2= 6
Итак, x^2-x-30= (x+5)(x-6)
<span>6tg2п/3ctg5п/6 =6tg(π-2π/3)ctg(π-5π/6)=6tgπ/3ctgπ/6=6*√3*√3=6*3=18</span>