Sina=8/17
cosa=√1-sin²a)=√(1-64/289)=√(225/289)=15/17
cosb=4/5
sinb=√(1-cos²b)=√(1-16/25)=√(9/25)=3/5
cos(a+b)=cosacosb-sinasinb=15/17*4/5-8/17*3/5=60/85-24/85=36/85
42х^2-35х+42х=15х+42х^2+49
42х^2-35х+42х-15х-42х^2-49=0
-8х-49=0
8х=-49
х=-49/8
х=- 6 1/8
135у^2-81у+2у=135у^2-63у+6,5
135у^2-81у+2у-134у^2+63у-6,5=0
-16у-6,5=0
16у=-6,5
160у=-65
у=-65/160
у=-13/32
а) f ⁾ (x)=2*2x+3=4x+3
б) f ⁾ (x)= 1/5*5x^4+4/x^5=x^4+4/x^5
в ) f ⁾ (x)=6*x^5-3*x^2
г) f ⁾ (x)= -2*3*x^2+2*2*x-1=6*x^2+4*x-1
F' = (sin'(5x)*sin(3x) + sin(5x)*sin'(3x)) + (cos'(5x)*cos(3x) + cos(5x)*cos'(3x)) = 5*cos(5x)*sin(3x) + 3cos(3x)*sin(5x) - 5sin(5x)*cos(3x) - 3sin(3x)*cos(5x) = 2sin(3x)*cos(5x) - 2sin(5x)*cos(3x) = 2*(sin(3x)*cos(5x) - sin(5x)*cos(3x)) = 2sin(3x-5x) = 2sin(-2x) = -2sin(2x)