问题
填空题
若x=30，那么
|
答案
-x x-3
+x+6 x2-3x 1 x
=
-x x-3
+x+6 x(x-3) 1 x
=
-x2 x(x-3)
+x+6 x(x-3) x-3 x(x-3)
=x2-x-6+x-3 x(x-3)
=x2-9 x(x-3)
=(x+3)(x-3) x(x-3)
=
，x+3 x
当x=30时，原式=
=30+3 30
．11 10
故答案是：
．11 10