★两道因式分解题`

1.10a^2+21xy-14ax-15ay=2a(5a-7x)-3y(5a-7y)=(5a-7x)(2a-3y)
2.x^4-x^2+(a^2+1)+a^2=x^4+2a^2+1-x^2
=(x^2+1)^2-x^2
=(x^2+x+1)(x^2+1-x)

1.10a^2+21xy-14ax-15ay
=(10a^2-15ay) -(14ax-21xy)
=5a(2a-3y)-7x(2a-3y)
=(2a-3y)(5a-7x);

2.题目没抄错?

10a^2+21xy-14ax-15ay
=10a^2-15ay-(14ax-21xy)
=5a(2a-3y)-7x(2a-3y)
=(5a-7x)(2a-3y)
x^4-x^2+(a^2+1)+a^2
=

1.10a^2+21xy-14ax-15ay
=2a(5a-7x)-3y(5a-7y)
=(5a-7x)(2a-3y)
2.x^4-x^2+(a^2+1)+a^2
=x^4+2a^2+1-x^2
=(x^2+1)^2-x^2
=(x^2+x+1)(x^2+1-x)
应该是这样

1.10a^2+21xy-14ax-15ay
=(10a^2-15ay) +(21xy-14ax)
=5a(2a-3y)-7x(2a-3y)
=(2a-3y)(5a-7x)
2. x^4-x^2+(a^2+1)+a^2不能分解,是否抄错了题?