f.2 因x分解

1. -64 + (12m - 5)2

= (12m - 5)2 - 82

= [(12m - 5) + 8][(12m – 5) - 8]

= (12m + 3)(12m - 13)

= 3(4m + 1)(12m - 13)

2. -48h2 + 12h + 6

= -6(8h2 – 2h - 1)

= -6(4h + 1)(2h - 1)

3. 3x2 – 48

= 3(x2 - 16)

= 3[x2 - 42]

= 3(x + 4)(x - 4)

4. 8u2 – 38uv – 33v2

= (4u + 3v)(2u – 11v)

5. abc – a2b – c2 + ac

= (abc – a2b) – (c2 - ac)

= ab(c - a) – c(c - a)

= (c - a)(ab - c)

1. -64+(12m-5)^2
=-[8^2 -(12m-5)^2]
=-(8+12m-5)(8-12m+5)
=-(3+12m)(13+12m)
2. -48h^2 +12h+6
=-6(8h^2 -2h-1)
=-6(4h+1)(2h-1)
3. 3x^2–48
=3(x^2-16)
=3[x^2-4^2]
=3(x + 4)(x - 4)
4. 8u^2 -38uv-33v^2
=(4u+3v)(2u-11v)
5. abc-a2b-c2+ ac
=(abc-a2b)-(c^2-ac)
=(c - a)(ab - c)