Question

(7-y)+3y=18怎么解

解方程3y(7-y)=18-y(3y-15)
已知3x-y=1/2,xy=2,求3x四次方y³-x³y四次方
对于任意自然数n试说明n(n+7)-(n-3)(n-2)

Answer 1

21y-3y^2=18-3y^2+15y
6y=18
y=3
原式=(3x-y)*(xy)^3
=(1/2)*8
=4
原式=n^2+7n-(n^2-5n+6)
=n^2+7n-n^2+5n+6
=12n+6