(x^2+3x+2)(x^2+7x+12)-120我做到(x+1)(x+2)(x+3)(x+4)-120就做不下去了顺便把想象的这道题目也做下吧(x+1)(x+2)(x+3)(x+4)+1但一定要思路!
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(x^2+3x+2)(x^2+7x+12)-120我做到(x+1)(x+2)(x+3)(x+4)-120就做不下去了顺便把想象的这道题目也做下吧(x+1)(x+2)(x+3)(x+4)+1但一定要思路!
(x^2+3x+2)(x^2+7x+12)-120
我做到(x+1)(x+2)(x+3)(x+4)-120就做不下去了
顺便把想象的这道题目也做下吧
(x+1)(x+2)(x+3)(x+4)+1
但一定要思路!
(x^2+3x+2)(x^2+7x+12)-120我做到(x+1)(x+2)(x+3)(x+4)-120就做不下去了顺便把想象的这道题目也做下吧(x+1)(x+2)(x+3)(x+4)+1但一定要思路!
(x^2+3x+2)(x^2+7x+12)-120
=(x+1)(x+2)(x+3)(x+4)-120
=(x^2+5x+4)(x^2+5x+6)-120
=[(x^2+5x+5)-][(x^2+5x+5)+1]-120
=(x^2+5x+5)^2-1-120
=(x^2+5x+5-11)(x^2+5x+5+11)
=(x^2+5x-6)(x^2+5x+16)
=(x-1)(x+6)(x^2+5x+16)
原式=(x+1)(x=4)*(x+2)(x+3)+1
=(x^2+5x+4)(x^2+5x+6)+1
=(x^2+5x+4)[(x^2+5x+4)+2]+1
=(x^+5x+4)^2+2(x^2+5x+4)+1
=[(x^2+5x+4)+1]^2
=(x^2+5x+5)^2
因为x^2+5x+5=(x+5/2)^2+(5/2根号5)^2>0恒成立,等价于判别式小于零,x^2+5x+5在实数范围内不可再分解,故这就是最后结果.
你做的对!
没什么疑问了。
(X^2+3x+2)(x^2+7x+12)-120
=(x+1)(x+2)(x+3)(x+4)-120
=(X^2+5x+4)(x^2+5x+6)-120
=(X^2+5x+4)^2+2(X^2+5x+4)-120
=(X^2+5x+4+12)(X^2+5x+4-10)
=(X^2+5x+16)(X^2+5x-6)
=(x-1)(x+6)(X^2+5...
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(X^2+3x+2)(x^2+7x+12)-120
=(x+1)(x+2)(x+3)(x+4)-120
=(X^2+5x+4)(x^2+5x+6)-120
=(X^2+5x+4)^2+2(X^2+5x+4)-120
=(X^2+5x+4+12)(X^2+5x+4-10)
=(X^2+5x+16)(X^2+5x-6)
=(x-1)(x+6)(X^2+5x+16)
(x+1)(x+2)(x+3)(x+4)+1
=[(x+1)(x+4)][(x+2)(x+3)]+1
=[(x^2+5x)+4][(x^2+5x)+6]+1
=(x^2+5x)^2+10(x^2+5x)+24+1
=(x^2+5x)^2+10(x^2+5x)+25
=(x^2+5x+5)^2
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