问题
解答题
计算下列各式的值: (1)(
(2)lg5lg20+(lg2)2. |
答案
(1)原式=(2
×31 3
)6+(2×21 2
)1 2
×1 2
-14 3
=2
×6×31 3
×6+21 2
×3 2
×1 2
-14 3
=22×33+2-1=109
(2)原式=lg5lg(5×4)+(lg2)2=lg5(lg5+lg4)+(lg2)2
=(lg5)2+lg5lg4+(lg2)2
=(lg5)2+2lg5lg2+(lg2)2
=(lg5+lg2)2
=1