-(6x-8)=10
-6x+8=10
-6x=10-8
-6x=2
-x=1/3
x=-1/3
Sin(x+a)*sin(x-a)= ¹/₂(cos(x+a-x+a)-cos(x+a+x-a))=
= ¹/₂ (cos2a-cos2x)= ¹/₂ (cos²a - sin²a - cos²x +sin²x)=
= ¹/₂ (1-sin²a-sin²a-1+sin²x+sin²x)= ¹/₂ (2sin²x -2sin²a)=
=sin²x - sin²a
1.5 = 3/2
18 1/3 = 55/3
3/2-1/4 = (3*2-1)/4= 5/4
5/4:55/3 = 5/4*3/55 = 3/(4*11) = 3/44