求这两道题简单容易看懂的速算技巧要详细步骤,越详细越好 求这两题目的答案,要步骤。 越详细越好
\u6c42\u8fd9\u4e24\u4e2a\u5708\u51fa\u6765\u7684\u7684\u9898\u7684\u8be6\u7ec6\u89e3\u9898\u6b65\u9aa4\uff0c\u8d8a\u8be6\u7ec6\u8d8a\u597d\u5373\u7528\u884c\u53d8\u6362\u628a\u77e9\u9635(A\uff0cE)\u5316\u6210(E\uff0cB)\u7684\u5f62\u5f0f\uff0c\u90a3\u4e48B\u5c31\u7b49\u4e8eA\u7684\u9006
\u5728\u8fd9\u91cc(A\uff0cE)=
1 0 0 1 0 0
1 3 0 0 1 0
2 -2 5 0 0 1 r2-r1,r3-2r1
\uff5e
1 0 0 1 0 0
0 3 0 -1 1 0
0 -2 5 -2 0 1 r2/3.r3+2r2,r3/5
\uff5e
1 0 0 1 0 0
0 1 0 -1/3 1/3 0
0 0 1 -8/15 2/15 1/5
\u8fd9\u6837\u5c31\u5df2\u7ecf\u901a\u8fc7\u521d\u7b49\u884c\u53d8\u6362\u628a(A,E)\uff5e(E,A^-1)
\u4e8e\u662f\u5f97\u5230\u4e86\u539f\u77e9\u9635\u7684\u9006\u77e9\u9635\u5c31\u662f
1 0 0
-1/3 1/3 0
-8/15 2/15 1/5
42\uff0c\uff081\uff09\u7528\u7a7a\u95f4\u5411\u91cf\u6765\u5427\uff0cA\u4e3a\u539f\u70b9\uff0cABx\u8f74\uff0cACy\u8f74\uff0cAA1z\u8f74\u3002
\u5411\u91cfAB\u4e3a{x\uff0c0,0}\uff0c\u5411\u91cfA1C\u4e3a{0,y,-y}
\u5219\u5411\u91cfAB\u00b7\u5411\u91cfA1C=0
\uff082\uff09A1C={0,y,-y}\uff0cBB1={0,0,y}
cos=|n\u00b7m|/(|n||m|)=-y^2/\u53822y\u00b7y=-\u53822/2
\u4e24\u7ebf\u5939\u89d2135\u00b0
43\uff0c\uff081\uff09F\uff08x\uff09=log\uff081/2\uff09 (1-x)/(1+x)
=log\uff081/2\uff09 8/2
=log\uff081/2\uff09 4
=-2
(2)f(m-2x)=log\uff081/2\uff09 (1-m+2x)
2f(m-2x)=log\uff081/2\uff09 (1-m+2x)^2
\u7531\u4e8elog\uff081/2\uff09 x\u4e3a\u51cf\u51fd\u6570\uff0c\u5219\u5f532f(m-2x)<=g(x)
(1-m+2x)^2>=x
(1-m)^2+(3-4m)x+4x^2>=0\u6052\u6210\u7acb
\u25b3<=0
16m^2-24m+9-16+32m-16m^2<=0
8m<=7
m<=7/8
3个数一组,三个数第一个数都是除以3余1,如果设第一个数是3n+1,第二个3n+2,第三3n+3,
3n+1+(3n+2)-(3n+3)=3n
第一组,3n+1=1,n=0
最后一组 3n+1=100, n=33
所以和为 3x0+3x1+3x2+...+3x33 = 3x(1+33)x33/2=1683
第二题
1005×10061006-1006×10051005
=1005x1006x10001-1006x1005x10001
=0
把10061006拆成1006x10001就好,10051005同样拆,会发现是三个相同数乘积的差,为0
望采纳,谢谢
第一题三个数一组就是
1+2-3+4+5-6+7+8-9+……+100+101-102=0+3×1+3×2+3×3+……+3×33
=3×(1+2+3+……33)
=3×(1+33)÷2×33
=1683
第二题
1005×10061006-1006×10051005
=1005×10061006-1005×10051005-10051005
=1005×(10061006-10051005)-10051005
=1005×10001-10051005
=10051005-10051005
=0
到底是谁这么无聊,整这种题
还不懂的话,还可以问我哦!( ⸍ꔷ͈ᗄꔷ͈⸌)o彡
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