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2x^方-(k+5)x-(k^方-2k-3)=04(x+1)^方=3(+2)x^方-3ax+2ax+2a^方-a-1=0

2017-03-25

2x^方-(k+5)x-(k^方-2k-3)=0
4(x+1)^方=3(+2)
x^方-3ax+2ax+2a^方-a-1=0

优质解答

x^2-3ax+2ax+2a^2-a-1=0
<=>x^2-ax+2a^2-a-1=0
<=>x^2-ax+a^2/4+7a^2/4-a-1=0.
<=>(x-a/2)2x^2-(k+5)x-(k+1)*(k-3)=0
<=>(2x+k-3)(x-k-1)=0.
=>x=(3-k)/2或x=k+1.
4(x+1)^2=3(x+2)
<=>4x^2+8x+4=3x+6
<=>4x^2+5x-2=0
<=>x^2+5x/4-1/2=0
<=>(x+5/8)^2=57/64.
<=>x=-(5+√57)/8或x=(√57-5)/8.
x^2-3ax+2ax+2a^2-a-1=0
<=>x^2-ax+2a^2-a-1=0
<=>x^2-ax+a^2/4+7a^2/4-a-1=0.
<=>(x-a/2)^2=-(7a^2-4a-4)/4=(4a+4-7a^2)/4.
=>x=[a-√(4a+4-7a^2)]/2或x=[a+√(4a+4-7a^2)]
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以上的问题中(2)(3)题有很大的问题.
初二题目有这么复杂?