负13乘3分之2减0.34乘7分之2加3分之1乘负13减7分之5乘0.34等于多少?用简便算法 (-13)×(2/3)-0.34×(2/7)+(1/3)×(-13)-(5/7)×0.34
问题描述:
负13乘3分之2减0.34乘7分之2加3分之1乘负13减7分之5乘0.34等于多少?
用简便算法 (-13)×(2/3)-0.34×(2/7)+(1/3)×(-13)-(5/7)×0.34
答
(-13)×(2/3+1/3)-0.34×(2/7+5/7)=-13.37
答
(-13)×(2/3)-0.34×(2/7)+(1/3)×(-13)-(5/7)×0.34
=(-13)x(2/3)+(1/3)x(-13)-0.34x(2/7)-(5/7)x0.34
=(-13)x(2/3+1/3)-0.34x(2/7+5/7)
= -13-0.34
= -13.34