因式分解!!!
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共4个回答
热心网友
首先将因式分解的结果（5x+by）（cx+y）展开得:
5c*x^2 + (5+bc)xy + b*y^2
该结果应与原多项式对应, 所以有
5c = a , 5+bc = -1 , b = -2
解得 a = 15 , b = -2 , c = 3
“^2”表示平方，“*”表示乘号
热心网友
(5x+by)(cx+y)
=5cx^2+5xy+bcxy+by^2
=5cx^2+(5+bc)xy+by^2
=ax^2-xy-2y^2
所以5c=a
5+bc=-1
b=-2
所以a=15
b=-2
c=3
明白了？？
热心网友
因为ax^2-xy-2y^2=5cx^2+(5+bc)xy+by^2
so ax^2=5cx^2
-xy=(5+bc)xy
-2y^2=by^2
so a=5c --------------1
5+bc=-1 ---------------2
b=-2 --------------3
so c=3
a=15
热心网友
a = 15 , b = -2 , c = 3
