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已知 19x 31 13x 17

(19x-13)(13x-17)-(17-13x)(11x-23) =(19x-13)(13x-17)+(13x-17)(11x-23) =(13x-17){19x-13+11x-23} =(13x-17)(30x-0) =30x(13x-17)

题目有误,没有d (19x-31)(13x-17)-(13x-17)(11x-24) =(19x-31-11x+24)(13x-17) =(8x-7)(13x-17) =104x^2-136x-91x+119 =104x^2-227x+119 (ax+b)(8x+c) =8ax^2+acx+8bx+bc =8ax^2+(ac+8b)x+bc (19x-31)(13x-17)-(13x-17)(11x-24...

A 试题分析:首先要对原式正确因式分解,然后进行对号入座,即可得出字母的值.解:原式=(13x﹣17)(19x﹣31﹣11x+23)=(13x﹣17)(8x﹣8),∵可以分解成(ax+b)(8x+c),∴a=13,b=﹣17,c=﹣8,∴a+b+c=﹣12.故选A.点评:各项有公因式...

原式=(13x-17)(19x-31-12x+23) =(13x-17)(7x-8) a=12 b=-17 c=-8 A+b+c=12-17-8=-13

(19x-31)(13x-7)-(13x-7)(11x-23)=(13x-7)[(19x-31)-(11x-23)]=(13x-7)(8x-8),则a=13,b=-7,c=-8.则a+b+c=13-7-8=-2.故选C.

因为: 11x13x17x19=46189, 所以: 3.8x8.5x11x39=(0.2×19)×(0.5×17)×11×(3×13) =(0.2×0.5×3)×(11×13×17×19)=0.3×46189=13856.7

11X13+13X17+17X19+19X23+23X29 =13X(11+17)+19X(17+23)+23X29 =13X28+19X40+23X28+23 =28X(13+23)+760+23 =30X36-2X36+783 =1080-72+783 =1080+711 =1791

13X+343=19.8(X-5), 13X+343=19.8X-99, 19.8X-13X=343-99, 6.8X=244, X=610/17,

(1)去分母得:6x=x+5,解得:x=1,经检验x=1是分式方程的解;(2)去分母得:2(3x-1)+3x=1,去括号得:6x-2+3x=1,解得:x=1,经检验x=1是分式方程的解.

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