Question

四点6×5点2+4点8×5点四的简便计算

鍥涚偣6脳5鐐�2+4鐐�8脳5鐐瑰洓鐨勭畝渚胯�绠�

Answer 1

解:4.6*5.2+4.8*5.4
=(4.9-0.3)(4.9+0.3)+(5.1-0.3)(5.1+0.3)
=4.9^2-0.3^2+5.1^2-0.3^2
=4.9^2+5.1^2-2*0.3^2
=4.9^2+5.1^2+2*5.1*4.9-2*5.1*4.9-0.18
=(5.1+4.9)^2-2*(5+0.1)*(5-0.1)-0.18
=10^2-2*(25-0.01)-0.18
=100-50+0.02-0.18
=50-0.16
=49.84

Answer 2

4.6*5.2+4.8*5.4
=4.6*5.2+4.8*4.6+4.8*0.6
=4.6*(5.2+4.8)+2.88
=46+2.88
=48.88