D=1,5
(5)=-8+1,5×4=2
(n)=-8+1,5×(n-1)
.............
<em>sin⁴α-cos⁴α+cos²α=(sin²α-cos²α)(sin²α+cos²α)+cos²α=sin²α-cos²α+cos²α=sin²α.</em>
<span>(х-у)2-(х+у)2/2=(x</span>²-2xy+y²-x²-2xy-y²)/2=-2xy
-2x
1) (y(y+1))/y^2=(y+1)/y
2) (a(a-2))/((a-2)(a+2)=a/(a+2)