分解因式.急.① 8x^2+22x+5 ② x^3-2x^2+1

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分解因式.急.① 8x^2+22x+5 ② x^3-2x^2+1
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分解因式.急.① 8x^2+22x+5 ② x^3-2x^2+1
分解因式.急.① 8x^2+22x+5 ② x^3-2x^2+1

分解因式.急.① 8x^2+22x+5 ② x^3-2x^2+1
① 8x^2+22x+5
=(4x+1)(2x+5)
② x^3-2x^2+1
=x³-x²-x²+1
=x²(x-1)-(x-1)(x+1)
=(x-1)(x²-x-1)

① 8x^2+22x+5
=(2x+5)(4x+1)
② x^3-2x^2+1
=x³-x²-x²+1
=x²(x-1)-(x-1)(x+1)
=(x-1)(x²-x-1)

① 8x^2+22x+5
=(2x+5)(4x+1)
② x^3-2x^2+1
=x^3-x^2-x^2+1
=x^2(x-1)-(x^2-1)
=x^2(x-1)-(x-1)(x+1)
=(x-1)(x^2-x-1)

(1)8x^2+22x+5
=(4x+1)(2x+5)
(2)x^3-2x^2+1
=x^3-x^2-x^2+1
=x^2(x-1)-(x^2-1)
=x^2(x-1)-(x-1)(x+1)
=(x-1)(x^2-x-1)

① 8x^2+22x+5
=(4x+1)(2x+5)
② x^3-2x^2+1
=x³-x²-x²+1
=x²(x-1)-(x-1)(x+1)
=(x-1)(x²-x-1)
=(x-1)(x-(1+√5)/2)(x-(1-√5)/2)

① 8x^2+22x+5
=(2x+5)(4x+1)
② x^3-2x^2+1
=x³-1-2x²+2
=(x-1)(x²+x+1)-2(x+1)(x-1)
=(x-1)[(x²+x+1)-2(x+1)]
=(x-1)(x²-x-1)
=(x-1)[x-(1+√5)/2][x-(1-√5)/2]

8x^2+22x+5=(2x+5)(4x+1)
x^3-2x^2+1=x^3-x^2-(x^2-1)=(x-1)(x^2-x-1)

(1)由十字相乘法,得:原式=(4x+1)(2x+5)
(2)先猜根,即猜测方程x³﹣2x²+1=0的根,显然x1=1
所以,原式=x³﹣x²﹣x²+1
=x²(x﹣1)﹣(x+1)(x﹣1)
=(x﹣1)(...

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(1)由十字相乘法,得:原式=(4x+1)(2x+5)
(2)先猜根,即猜测方程x³﹣2x²+1=0的根,显然x1=1
所以,原式=x³﹣x²﹣x²+1
=x²(x﹣1)﹣(x+1)(x﹣1)
=(x﹣1)(x²﹣x﹣1)
=(x﹣1)(x﹣x2)(x﹣x3)
式中,x2,x3是方程x²﹣x﹣1=0的两根,所以x2=½(1+√5),x3=½(1﹣√5)

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