Question

3.6*42.3*3.75-12.5*0.423*2.8怎样算最简便

Answer 1

错了，后面三个中小数点有一个错了
假设是3.6*42.3*3.75-12.5*0.423*28
=0.9*42.3*4*3.75-0.125*4*42.3*7
=0.9*42.3*15-0.5*42.3*7
=42.3*(0.9*15-0.5*7)
=42.3*(13.5-3.5)
=42.3*10
=423

Answer 2

令a=√x+√y
a²=x+y+2√xy=1+2√xy

1=x+y>=2√xy
2√xy<=1
所以1+2√xy<=2
即0<a²<=2
0<a<=√x
即√x+√y最大是√2
所以m≥√2