Question

9.8x2五的简便运算？

Answer 1

解：9.8x2等于（ 98/5 ），【即等于19.6】
∵已知需求出9.8x2等于多少
(B - C)× A = B × A - C × A
∴9.8 x 2
= （10 - 0.2）× 2
= 10 × 2 - 0.2 × 2
= 20 - 0.4
= 100/5 - 2/5
= 98/5
= 19.6
答：9.8x2等于98/5，【即等于19.6】

Answer 2

解：依题意得算式，
9.8×25
=（10-0.2）×25
=10×25-0.2×25
=250-5
=245
即9.8×25=245

Answer 3

本题用乘法分配律计算：
9.8*2
=(10-0.2)*2
=10*2-0.2*2
=20-0.4
=19.6

Answer 4

解:9.8*25
=9.8*(25x4)÷4
=9.8*100÷4
=980÷4
=245

Answer 5

9.8×25
=4.9×2×25
=4.9×50
=49×5
=245