七年级数学下册《二元一次方程组》计算题新人教版.doc

1、2019-2020学年七年级数学下册二元一次方程组计算题 新人教(2)(4)(6)rx _2 y = 0lX=3 y+12P_3q=133m _2n = 5(1)19"3x _5y = 7(2) J：4x +2y =5r6x _5y - 11(3) J4 x 14y = 7(4)41X.9 y= 1254l-4x +3y = -5ix +以2(5) 5 «)350.5x -0.3 y = 0.21、w 4m -2n 5- 013 n4m- 6O4x+ 0.3户 0.7'Jlx- 10y= 1'5x + 2y = 5a(6)l3x + 4y = 3a11-x

2、y = 12> J 231 1!_ x=_233其中a为常数）、2x + 2 y= 75、6、<2x_lly =3c（c为常数）<6x +29 y= -7c-2 y= 0（1），+3x +2 y= 8<_x_4y =j（c、d为常数）4x+3y = 2d-cf 2x_y（2）f二3i 33f3x + 4y = 2（3） J1 2x _y = 51'a+ b = 3（41a+c =4b+c=5"2x _ y = 5j（用代入法）3x +4y = 2x _ 2y = - 2,2x +3y 6X + 2 y= 9 l3x - 2y = -13（x-l）= y

3、 + 5宇. 11 35x 与 y = -3* 2x +3y -z =5I .3x +y +2z =113x -5z =G +4 z = - 15jm - n = 22m +3n = 144(x - -y 与 3(4 y尸2x y!一 + = 2b 3x +2 y =150(1)'4x 6y 34)0 ( 2)；3x+7y= 9(1)4x-7y= 5 (2)；3x-4y = 10(1)5x +6y = 42 (2)m nj + =13彳2 3m n 二33 43(x + y)4 隹-y ) = 41 x+y x-y一 + =1263x +2y = 52x -y = 8x + 4 y=

4、4A = 21 3 4< 3-4 y=- 7'x 1 y+ 2i-= 0! 3 4L二二LI 236用代人法解 x =3y、2x 5y - 4，2x +3y = 15用加诚法解2x.2y =5(1)5x +y =7、4x -3y -17：4x -3y =52x -y =2x + y -z =13(2)x-y+z=3I1x + y +z =93x -5 y= 92x+3y = -62 X+3Y=03X -Y =11x + y = 54 y +z = 6,z +x= 7u2345l *'7 x Ty 5x 16"2x +2y =8*2x -2y = 4x - 2 y=z ，3x + 2 y= 12 x- y=z +2 xl =-4z-2y =-1 J七7 =-1i = 5,(1)(2)2x +3 y 15= 0;3x + 2y= 9,'5x+y+ z= 4,I(3) <2x -3 y+ 8z = 1,5 y - 3x = - 2;(3x 5 yz =0;(4)x y = 3m, v y + z = 4m, iZ +x =5m.'x y + 10-彳= 95,42.20% , x 10% y 300 10%;