1.有一种新的运算符号“*”,规定:1*3=1×2×3;4*5=4×5×6×7×8.那么(6*4)÷(3*4)=?2.如果(□÷25+0.4×□)×25=187×25,那么□=?3.计算(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/02 01:56:11
![1.有一种新的运算符号“*”,规定:1*3=1×2×3;4*5=4×5×6×7×8.那么(6*4)÷(3*4)=?2.如果(□÷25+0.4×□)×25=187×25,那么□=?3.计算(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5](/uploads/image/z/13370908-4-8.jpg?t=1.%E6%9C%89%E4%B8%80%E7%A7%8D%E6%96%B0%E7%9A%84%E8%BF%90%E7%AE%97%E7%AC%A6%E5%8F%B7%E2%80%9C%2A%E2%80%9D%2C%E8%A7%84%E5%AE%9A%EF%BC%9A1%2A3%3D1%C3%972%C3%973%EF%BC%9B4%2A5%3D4%C3%975%C3%976%C3%977%C3%978.%E9%82%A3%E4%B9%88%EF%BC%886%2A4%29%C3%B7%283%2A4%29%3D%3F2.%E5%A6%82%E6%9E%9C%EF%BC%88%E2%96%A1%C3%B725%2B0.4%C3%97%E2%96%A1%EF%BC%89%C3%9725%3D187%C3%9725%2C%E9%82%A3%E4%B9%88%E2%96%A1%3D%3F3.%E8%AE%A1%E7%AE%97%EF%BC%881%2B1%EF%BC%8F2%2B1%EF%BC%8F3%2B1%EF%BC%8F4%EF%BC%89%C3%97%EF%BC%881%EF%BC%8F2%2B1%EF%BC%8F3%2B1%EF%BC%8F4%2B1%EF%BC%8F5%EF%BC%89%EF%BC%8D%EF%BC%881%2B1%EF%BC%8F2%2B1%EF%BC%8F3%2B1%EF%BC%8F4%2B1%EF%BC%8F5)
1.有一种新的运算符号“*”,规定:1*3=1×2×3;4*5=4×5×6×7×8.那么(6*4)÷(3*4)=?2.如果(□÷25+0.4×□)×25=187×25,那么□=?3.计算(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5
1.有一种新的运算符号“*”,规定:1*3=1×2×3;4*5=4×5×6×7×8.那么(6*4)÷(3*4)=?
2.如果(□÷25+0.4×□)×25=187×25,那么□=?
3.计算(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)×(1/2+1/3+1/4)(l例如:1/4这样的,是分数)
4.计算:(1/8+1/24+1/48+1/80+1/120+1/168=1/224+1/288)×128
1.有一种新的运算符号“*”,规定:1*3=1×2×3;4*5=4×5×6×7×8.那么(6*4)÷(3*4)=?2.如果(□÷25+0.4×□)×25=187×25,那么□=?3.计算(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5
1.2.问自己想就能做出来.最多第一题提醒一下:第一个数是第一个乘数,第二个数指从第一个数开始,依次加一,共乘以【第二个数的数量】的这么多数.
3.随便拆一个括号,运用乘法分配率,很容易得出来答案
4.没打错吧?怎么还出来个“=”号?应该是+号吧.
都拆开,很容易发现括号里的都能提出1/8来,1/8和括号外的128相乘得到16,括号里只有(1+ 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 +1/36),然后再提公因数,把1/3 + 1/6 变成1/3 *(1 + 1/2)=1/3 * 3/2=1/2,把1/10 + 1/15 变成1/5*(1/2 + 1/3)=1/5 * 5/6=1/6,把 1/21 + 1/28 变成1/7*(1/3 + 1/4)=1/7 * 7/12=1/12.得出(1+ 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 +1/36)=(1+ 1/2 + 1/6 + 1/12 + 1/36)=【1+ 1/2 + 1/6* (1+ 1/2) + 1/36】=【(1+ 1/2)(1+ 1/6)+1/36】=7/4 +1/36=16/9,所以原式=16/9 *16=256/9