计算 (1)(−48a6b5c)÷(24ab4)•(−5/6a5b2); (2)(2s-3t+1)(2s+3t-1).
问题描述:
计算
(1)(−48a6b5c)÷(24ab4)•(−
a5b2);5 6
(2)(2s-3t+1)(2s+3t-1).
答
(1)原式=-2a5bc•(-
a5b2)5 6
=
a10b3c;5 3
(2)原式=[2s-(3t-1)][2s+(3t-1)]
=(2s)2-(3t-1)2
=4s2-9t2+6t-1.