У = 6х -12 = 18
у = 18
-------------------
6х - 12 = 18
6х = 18 + 12
6х = 30
х = 5
----------------------------------
у = 6*5 - 12
у = 30 - 12
у = 18
=(y^3+5y)(y-3)=y^4+y^3(-3)+5y^3-15y^2=y^4-3y^3+5y^3-15y^2=y^4+2y^3-15y^2
(a+7b)(a-7b)=a²+7ab-7ab-49b²=a²-49b²
<span>2 ( d - 5 ) d - ( d + 1)^3</span>
<span>2d-10d-3d+1=0</span>
<span>2d-10d-3d=-1</span>
<span>-11d=-1</span>
<span>d=1/11</span>