<span>sin2xcos3c=0
sin2x=0⇒2x=πn⇒x=πn/2
cos3x=0⇒3x=π/2+πn⇒x=π/6+πn/3</span>
2a+3b>a-2b
2а-а>-2b-3b
a>-5b
8) 11/2x-5 + 9x+5/-(2x-5)=11-9x+5 /2x-5=16-9x/2x-5
9) 4x/y(5y-2x) - 25y/x(5y-2x)=4x^2-25y^2/xy(5y-2x)=(2x-5y)(2x+5y)/xy(5y-2x)=2x+5y/xy
12) 12/(3a+4b)(3a-4b) - 2/(a(3a-4b)=12a-6a-8b/a(3a+4b)(3a+4b)=6a-8b/a(3a-4b)(3a+4b)=2(3a-4b)/a(3a-4b)(3a+4b)=2/a(3a+4b)
А17= а16+d
A17= 47-9= 38
a19= -21+3= -18