15а+30=12а+42 15с+10=72-16с
15а-12а=42-30 15с+16с=72-10
3а=12 31с=62
а=12:3 с=62:31
а=4 с=2
(соs u)⁾= -sin u*u⁾
a) (10cos(10x) ) ⁾ = -10sin(10x) *10 = - 100sin(10x)
b) ( - cos(10x) -45) ⁾ = - sin(10x) *10 +0 = - 10sin(10x)
d) ( - 0,1cos(10x) +41) ⁾ = 0,1sin(10x) *10+0 = sin(10x)
c) ( -0,1cos(10x) ) ⁾ = 0,1 sin(10x) *10 = sin(10x)
подходят с и d
15*x-1690=1355
15х=1355+1690
15х= 3045
Х=3045:15
Х= 203.