七年级数学题
\u4e03\u5e74\u7ea7\u6570\u5b66\u98981.\u7531\u4e8e\u25b3APQ\u4e3a\u7b49\u8170\u4e09\u89d2\u5f62
\u6240\u4ee5\u2220A=\u2220APQ
\u7531\u4e8e\u2220A=30\u00b0
\u6240\u4ee5\u2220AQP=120\u00b0
\u6240\u4ee5\u2220AQP=120\u00b0
\u7531\u4e8e\u2220A\u2018=45\u00b0
\u6240\u4ee5\u2220ACA\u2018=15\u00b0
\u6240\u4ee5\u03b8=\u2220ACA\u2018=15\u00b0
2.\u5728\u77e9\u5f62\u4e2d\uff0c\u957f\u5bbd\u4ee5\u53ca\u5bf9\u89d2\u7ebf\u90fd\u662f\u6574\u6570\u610f\u5473\u7740\uff0c\u5728\u7531\u957f\uff08a\uff09\u5bbd\uff08b\uff09\u548c\u5bf9\u89d2\u7ebf\uff08c\uff09\u6784\u6210\u7684\u76f4\u89d2\u4e09\u89d2\u5f62\u4e2d\uff0ca^2+b^2=c^2\u4e14a,b,c\u5747\u4e3a\u6b63\u6574\u6570
\u6240\u4ee5a,b,c\u6ee1\u8db3a=k(m^2-n^2),b=2kmn,c=k(m^2+n^2)\uff08\u5176\u4e2dk,m,n\u5747\u4e3a\u6b63\u6574\u6570\uff09
\u6240\u4ee5\u77e9\u5f62\u9762\u79ef\u4e3aS=ab=2k^2*mn*(m-n)*(m+n)
1.\u82e5m,n\u9664\u4ee53\u4f59\u6570\u76f8\u540c\uff0c\u5373m\u2261n(mod 3)\uff0c\u5219m-n\u5fc5\u80fd\u88ab3\u6574\u9664\uff0c\u53c8\u56e0\u4e3am,n,(m-n),(m+n)\u5176\u4e2d\u81f3\u5c11\u6709\u4e00\u4e2a\u662f\u5076\u6570\uff0c\u6240\u4ee5S\u80fd\u88ab12\u6574\u9664\uff1b\uff08\u5305\u542b\u4f59\u6570\u5bf9\u4e3a,,\uff09
2.\u82e5m,n\u5206\u522b\u9664\u4ee53\u540e\uff0c\u4f59\u6570\u4e4b\u548c\u4e3a3\u62160\uff0c\u5219(m+n)\u5fc5\u80fd\u88ab3\u6574\u9664\uff0c\u53c8\u56e0\u4e3am,n,(m-n),(m+n)\u5176\u4e2d\u81f3\u5c11\u6709\u4e00\u4e2a\u662f\u5076\u6570\uff0c\u6240\u4ee5S\u80fd\u88ab12\u6574\u9664\uff1b\uff08\u5305\u542b\u4f59\u6570\u5bf9\u4e3a,\uff09
3.\u82e5m,n\u4e2d\u6709\u4e00\u4e2a\u9664\u4ee53\u4f590\uff0c\u5219m\u548cn\u4e2d\u6709\u4e00\u4e2a\u5fc5\u80fd\u88ab3\u6574\u9664\uff0c\u53c8\u56e0\u4e3am,n,(m-n),(m+n)\u5176\u4e2d\u81f3\u5c11\u6709\u4e00\u4e2a\u662f\u5076\u6570\uff0c\u6240\u4ee5S\u80fd\u88ab12\u6574\u9664\uff1b\uff08\u5305\u542b\u4f59\u6570\u6709\u4e00\u4e2a\u4e3a0\u7684\u6240\u6709\u60c5\u51b5\uff09
\u4e0a\u9762\u4e09\u79cd\u60c5\u51b5\u5305\u542b\u4e86\u6240\u6709\u4f59\u6570\u7684\u60c5\u51b5
\u7efc\u4e0a\u6240\u8ff0\uff0cS\u603b\u80fd\u88ab12\u6574\u9664\uff0c\u6240\u4ee5\u8fd9\u4e2a\u77e9\u5f62\u7684\u9762\u79ef\u5fc5\u4e3a12\u7684\u500d\u6570
\u9996\u5148\u8fd9\u9053\u9898\u4f60\u8981\u8bc1\u660eDE+BE=CE \u5c31\u9700\u8981\u8bc1\u660e\u4e09\u89d2\u5f62ACD\u5168\u7b49\u4e8e\u4e09\u89d2\u5f62BCE
\u5475\u5475 \u4f60\u8fd9\u4e2a\u56fe\u753b\u7684\u5f88\u4e0d\u7cbe\u7ec6\u54e6 \u4e0b\u9762\u5f00\u59cb\u8bc1\u660e
\u56e0\u4e3a\u89d2ACB=90 \u6240\u4ee5\u89d2ACD+\u89d2BCD=90
\u53c8\u56e0\u4e3aAD\u5782\u76f4\u4e8eCE \u6240\u4ee5\u89d2CAD+\u89d2ACD=90
\u6240\u4ee5\u89d2CAD=\u89d2BCD
\u53c8\u56e0\u4e3aAC=BC \u6839\u636e\u89d2\u8fb9\u89d2\uff08\u6216\u8005\u89d2\u89d2\u8fb9\uff09\u8bc1\u660e\u4e09\u89d2\u5f62ACD\u5168\u7b49\u4e8e\u4e09\u89d2\u5f62BCE
\u6240\u4ee5BE=CD \u6240\u4ee5BE+DE=CD+DE=CE
\u6c42\u91c7\u7eb3 \u5475\u5475
x=1时，px³+qx+1=2001
p+q+1=2001
p+q=2000
x=-1时：
px³+qx+1
=-p-q+1
=-2000+1
=-1999
所以：
当x=1时,代数式px的三次方+qx+1的值是2001,则当x=-1时,
代数式px的三次方+qx+1的值是-1999
∵x=1时，代数式px^3+qx+1的值为2001
∴p+q+1=2001
x=-1时
px^3+qx+1
＝-p-q+1
=-p-q-1+2
=-(p+q+1)+2
=-2001+2
=-1999
x=1时，p+q+1=2001
p+q=2000
所以x=-1时，-p-q+1=-1999
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绛旓細绛旀锛歺=48 y=47 (2) 18x+23y=2303 74x-y=1998 绛旀锛歺=27 y=79 (3) 44x+90y=7796 44x+y=3476 绛旀锛歺=79 y=48 (4) 76x-66y=4082 30x-y=2940 绛旀锛歺=98 y=51 (5) 67x+54y=8546 71x-y=5680 绛旀锛歺=80 y=59 (6) 42x-95y=-1410 21x-y=1575 绛旀锛歺=75 y...
