七年级一道数学题目
(1)阅读理解我们知道,正方形面积越大,其边长也越大,即如果0<a<b,那么0<√a<√b因为1²<2<2²,所以1<√2<2,可知√2的整数部分是1...
(1)阅读理解
我们知道,正方形面积越大,其边长也越大,即如果0<a<b,那么0<√a<√b
因为1²<2<2²,所以1<√2<2,可知√2的整数部分是1.
(i)取1+2分之2=1.5,由1.5²=2.25>2,得1<√2<1.5.
(ii)取1+1.5分之2=1.25,由1.25²<1.6<2,得1.25<√2<1.5
(2)操作实践
继续像(i)(ii)那样取值和比较,确定√2的十分位和百分位上的数字.问题补充:
√为根号 , 请把过程一起写出 展开
我们知道,正方形面积越大,其边长也越大,即如果0<a<b,那么0<√a<√b
因为1²<2<2²,所以1<√2<2,可知√2的整数部分是1.
(i)取1+2分之2=1.5,由1.5²=2.25>2,得1<√2<1.5.
(ii)取1+1.5分之2=1.25,由1.25²<1.6<2,得1.25<√2<1.5
(2)操作实践
继续像(i)(ii)那样取值和比较,确定√2的十分位和百分位上的数字.问题补充:
√为根号 , 请把过程一起写出 展开
4个回答
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你的解题步骤本来就有错
(i)(ii)这两行都有错,所以不可能仿照做!应该如下:
1)取(1+2)/2=1.5,由1²<2<1.5²=2.25,得1<√2<1.5. (你的题目分子分母弄错了)
2)取(1+1.5)/2=1.25,由1.25²<2<2.25,得1.25<√2<1.5
3)取(1.25+1.5)/2=1.375,由1.375²<2<1.5²,得:1.375<√2<1.5
4)取(1.375+1.5)/2=1.4375,由1.375²<2<1.4375^2,得1.375<√2<1.4375
5)取(1.375+1.4375)/2=1.40625,由1.40625²<2<1.4375²,得1.40625<√2<1.4375
6)取(1.40625+1.4375)/2=1.421875,由1.40625²<2<1.421875²,得1.40625<√2<1.421875
7)取(1.40625+1.421875)/2=1.4140625,由1.4140625²<2<1.421875²,
得1.4140625<√2<1.421875
8)取(1.4140625+1.421875)/2=1.41796875由1.4140625²<2<1.41796875²,
得1.4140625<√2<1.41796875
结论:√2≈1.41 (越往后越精确)
(i)(ii)这两行都有错,所以不可能仿照做!应该如下:
1)取(1+2)/2=1.5,由1²<2<1.5²=2.25,得1<√2<1.5. (你的题目分子分母弄错了)
2)取(1+1.5)/2=1.25,由1.25²<2<2.25,得1.25<√2<1.5
3)取(1.25+1.5)/2=1.375,由1.375²<2<1.5²,得:1.375<√2<1.5
4)取(1.375+1.5)/2=1.4375,由1.375²<2<1.4375^2,得1.375<√2<1.4375
5)取(1.375+1.4375)/2=1.40625,由1.40625²<2<1.4375²,得1.40625<√2<1.4375
6)取(1.40625+1.4375)/2=1.421875,由1.40625²<2<1.421875²,得1.40625<√2<1.421875
7)取(1.40625+1.421875)/2=1.4140625,由1.4140625²<2<1.421875²,
得1.4140625<√2<1.421875
8)取(1.4140625+1.421875)/2=1.41796875由1.4140625²<2<1.41796875²,
得1.4140625<√2<1.41796875
结论:√2≈1.41 (越往后越精确)
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(1.25+1.5)=1.375
1.375^2<2<1.5^2
1.375<√2<1.5
(1.375+1.5)/2=1.4375
1.375^2<2<1.4375^2
1.375<√2<1.4375
(1.375+1.4375)/2=1.40625
1.40625^2<2<1.4375^2
1.40625<√2<1.4375
(1.40625+1.4375)/2=1.421875
1.40625^2<2<1.421875^2
1.40625<√2<1.421875
(1.40625+1.421875)/2=1.4140625
1.4140625^2<2<1.421875^2
1.4140625<√2<1.421875
(1.4140625+1.421875)/2=1.41796875
1.4140625^2<2<1.41796875^2
1.4140625<√2<1.41796875
√2=1.41
1.375^2<2<1.5^2
1.375<√2<1.5
(1.375+1.5)/2=1.4375
1.375^2<2<1.4375^2
1.375<√2<1.4375
(1.375+1.4375)/2=1.40625
1.40625^2<2<1.4375^2
1.40625<√2<1.4375
(1.40625+1.4375)/2=1.421875
1.40625^2<2<1.421875^2
1.40625<√2<1.421875
(1.40625+1.421875)/2=1.4140625
1.4140625^2<2<1.421875^2
1.4140625<√2<1.421875
(1.4140625+1.421875)/2=1.41796875
1.4140625^2<2<1.41796875^2
1.4140625<√2<1.41796875
√2=1.41
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