(1) 3x2+7x+2 =(3x+1)(x+2) |
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(2) 4x2−11xy+6y2 =(4x−3y)(x−2y) |
(3) 27x3+8y3 =(3x)3+(2y)3 =(3x+2y)(9x2−6xy+4y2) |
(4) 216x3−1 =(6x)3−(1)3 =(6x−1)(36x2+6x+1) |
(5) −64x3+144x2y−108xy2+27y3 =−(64x3−144x2y+108xy2−27y3) =−{(4x)3−3・(4x)2・3 +3・(4x)・32−(3y)3} =−(4x−3)3 |
(6) x3y+256−16xy−16x2 =x(x2−16)y−16(x2−16) =(x2−16)(xy−16) =(x+4)(x−4)(xy−16) |
(7) 2(2x−1)2−11(2x−1)+15 =2A2−11A+15 =(2A−5)(A−3) =(4x−2−5)(2x−1−3) =(4x−7)(2x−4) |
(8) x2−y2+6y−9 =x2−(y2−6y+9) =x2−(y−3)2 ={(x+(y−3)}{x−(y−3)} =(x+y−3)(x−y+3) |
(9) x4−29x2+100 =(x2−4)(x2−25) =(x+2)(x−2)(x+5)(x−5) |
(10) x4−16y4 =(x2)2−(4y2)2 =(x2+4y2)(x2−4y2) =(x2+4y2)(x+2y)(x−2y) |
(11) x4−x2−12 =(x2−4)(x2+3) =(x+2)(x−2)(x2+3) |
(12) 2x6+3x3−2 =2(x3)2+3x3−2 =(2x3−1)(x3+2)
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(13) x6−1 =(x3)2−1 =(x3+1)(x3−1) =(x+1)(x2−x+1)(x−1)(x2+x+1) =(x+1)(x−1)(x2+x+1)(x2−x+1)
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(14) (x2−7x)+4(x2−7x)−96 =(x2−7x+12)(x2−7x−8) =(x−3)(x−4)(x−8)(x+1) |
(15) 3x2y−xy2−2xy+3x−y−2 =xy(3x−y−2)+3x−y−2 =(xy+1)(3x−y−2) |
(16) 6x2+5xy+y2+x+y−2 =6x2+(5y+1)x+y2+y−2 =6x2+(5y+1)x+(y−1)(y+2) =(2x+y−1)(3x+y+2) |
(17) 7x2+4xy−3y2+15x−5y+2 =7x2+(4y+15)x−(3y2+5y−2) =7x2+(4y+15)x−(3y−1)(y+2) =(x+y+2)(7x−3y+1)
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(18) 8x2−yz+xz−8xy =8x2+xz−8xy−yz =(8x+z)x−(8x+z)y =(8x+z)(x−y) |
(19) 2x3+5x2y+4x2z−12xy2+10xyz−12y2z =2x3+5x2y−12xy2+4x2z+10xyz−12y2z =(2x3+5x2y−12xy2)x+2z(2x3+5x2y−12xy2) =(2x−3y)(x+4y)x+2z(2x−3y)(x+4y) =(2x−3y)(x+4y)(x+2z) |
(20) (2x+y)(y+z)(2x+z)+2xyz ={(y+z)(2x+z)}(2x+y)+2xyz ={z2+(2x+y)z+2xy}(2x+y)+2xyz =(2x+y)z2+(4x2+4xy+y2)z+4x2y+2xy2+2xyz =(2x+y)z2+(4x2+6xy+y2)z+2xy(2x+y) =(2x+y+z){(2x+y)z+2xy} =(2x+y+z)(2xz+yz+2xy) |