简便计算 (1)36×64+36² (2)(5×1/2)²-(4×1/2)²
问题描述:
简便计算 (1)36×64+36² (2)(5×1/2)²-(4×1/2)²
答
(1)36×64+36²
=36×(64+36)
=36×100
=3600
(2)(5×1/2)²-(4×1/2)²
=5²×(1/2)²-4²×(1/2)²
=(5²-4²)×(1/2)²
=(5+4)×(5-4)×(1/2)²
=9×1×(1/4)
=9/4
答
36×64+36²
=36×(64+36)
=36×100
=3600
(5×1/2)²-(4×1/2)²
=2.5²-2²
=(2.5+2)×(2.5-2)
=4.5×0.5
=2.25
答
(1)36×64+36²
=36×(64+36)
=36×100
=3600
(2)(5×1/2)²-(4×1/2)²
=(5/2+4/2)×(5/2-4/2) 【平方差公式】
=(9/2)×(1/2)
=9/4