▲1.8×2.5+0.5+0.42×1.8
= (1.8×2.5+0.42×1.8)+0.5
【提取公因数1.8】
= 1.8×(2.5+0.42)+0.5
=1.8x2.92+0.5
=1.8x(3-0.08)+0.5
=5.4-0.144+0.5
=5.9-0.144
=5.756
或
▲ 1.8×2.5+0.5+0.42×1.8
=0.9x2x2.5+0.5+0.042x9x2
=0.9x5+0.5+0.378x2
=4.5+0.5+0.756
=5.756
提出1.8,把2.5和0.42相加乘以1.8再加0.5
1.8×(2.5+0.42)+0.5
用手机计算器算最简单
把1.8提出来