A5=a2+3d
7=1+3d
d=2
a1=-1
a1000=-1+2*999
a1000=1997
8x -1.6 =1.8x -5.7
8x -1.8x =1.6 -5.7
6.2x = -4.1
x = -4.1 : 6.2
x = -41/10 * 10/62
x = -41/62
Sin7α Cosα + Cos7αSinα = Sin(7α +α) = Sin8α
Ответ:
Объяснение:
(7x+7y)(-6x-4)-(-x+9y)(5x+1)=-42x²-28x-42xy-28y-(-5x²-x+45xy+9y)=
=-42x²-28x-42xy-28y+5x²+x-45xy-9y=-37x²-87xy-27x-37xy=