下面是某同学对多项式(x2-4x+2)(x2-4x+6)+4进行因式分解的过程
解:设x2-4x=y原式=(y+2)(y+6)+4(第一步)=y2+8y+16(第二步)=(y+4)2(第三步)=(x2-4x+4)2(第四步)若x²+x=1,...
解:设x2-4x=y 原式=(y+2)(y+6)+4 (第一步) = y2+8y+16 (第二步) =(y+4)2 (第三步) =(x2-4x+4)2 (第四步)
若x²+x=1,试求(x-1)x(x+1)(x+2)+1的值. 展开
若x²+x=1,试求(x-1)x(x+1)(x+2)+1的值. 展开
2个回答
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( x" - 4x + 2 )( x" - 4x + 6 ) + 4
= [ ( x" - 4x ) + 2 ][ ( x" - 4x ) + 6 ] + 4
= ( x" - 4x )" + 8( x" - 4x ) + 12 + 4
= ( x" - 4x )" + 2 X 4 ( x" - 4x ) + 4"
= ( x" - 4x + 4 )"
= ( x" - 2 X 2x + 2" )"
= [ ( x - 2 )" ]"
= ( x - 2 )^4
x" + x = 1
x (x + 1) = 1
( x - 1 ) x ( x + 1 )( x + 2 ) + 1
= ( x - 1 )( x + 2 ) + 1
= x" + 2x - x - 2 + 1
= x" + x - 1
= 1 - 1
= 0
= [ ( x" - 4x ) + 2 ][ ( x" - 4x ) + 6 ] + 4
= ( x" - 4x )" + 8( x" - 4x ) + 12 + 4
= ( x" - 4x )" + 2 X 4 ( x" - 4x ) + 4"
= ( x" - 4x + 4 )"
= ( x" - 2 X 2x + 2" )"
= [ ( x - 2 )" ]"
= ( x - 2 )^4
x" + x = 1
x (x + 1) = 1
( x - 1 ) x ( x + 1 )( x + 2 ) + 1
= ( x - 1 )( x + 2 ) + 1
= x" + 2x - x - 2 + 1
= x" + x - 1
= 1 - 1
= 0
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