1 |
2(x+3) |
1 |
x−3 |
x |
2(x+3)(x−3) |
=
x−3−2(x+3)+x |
2(x+3)(x−3) |
=-
9 |
2(x+3)(x−3) |
(2)原式=[
a+2 |
a(a−2) |
8 |
(a+2)(a−2) |
a |
a−2 |
=
(a+2)2−8a |
a(a+2)(a−2) |
a |
a−2 |
=
(a−2)2 |
a(a+2)(a−2) |
a |
a−2 |
=
1 |
a+2 |
(3)552×3-452×3
=3×(552-452)
=3×(55+45)×(55-45)
=3×100×10
=3000;
(4)662+652-130×66
=662+652-2×65×66
=(66-65)2
=12
=1.