配方法因式分解!急!!!!

1.10m^2-21m+2=10(m^2-21m/10+441/400)+2-441/40
=10(m-21/20)²-361/40
=10[(m-21/20)²-(19/20)²]
=10(m-21/20+19/20)(m-21/20-19/20)
=10(m-1/10)(m-2)
=(10m-1)(m-2)
2.6y^2+y-35=6(y²+y/6+1/144)-1/24-35
=6(y+1/12)²-841/24
=6[(y+1/12)²-(29/12)²]
=6(y+1/12+29/12)(y+1/12-29/12)
=6(y+5/2)(y-7/3)
=(2y+5)(3y-7)
3.8t^2-22t+15=8(t²-11t/4+121/64)+15-121/8
=8(t-11/8)²-1/8
=8[(t-11/8)²-(1/8)²]
=8(t-11/8+1/8)(t-11/8-1/8)
=8(t-5/4)(t-3/2)
=(4t-5)(2t-3)

1 (10m-1)(m-2)
2 (2y+5)(3y-7)
3 (2t-3)(4t-5)