1.(x+1)×(x+2)-x(x-1)
=x²+2x+x+2-x²+x
=4x+2
2.9×11×101×10001
=(10-1)(10+1)×101×10001
=(100-1)×(100+1)×10001
=(10000-1)(10000+1)
=100000000-1
=99999999
1.(x+1)×(x+2)-x(x-1)
=x²+2x+x+2-x²+x
=4x+2
2.9×11×101×10001
=(10-1)(10+1)×101×10001
=(100-1)×(100+1)×10001
=(10000-1)(10000+1)
=100000000-1
=99999999