maths! maths! maths!－rlz87tm45t的部落格

標題:

maths! maths! maths!

發問:

p. 91. Solve the following systems of equations by the method of substiution.a. {a+3b=18 3a+5b=34b. {16w=5-4s 3s-8=8w+72. Solve the following systems of equations by the method of elimination.a. {5x-2y=6 3x+2y=10b. {6x-y-4/3=10 y+3x-7/4=13. Solvea. {5x+6y=1 4/3 x-2y= 8/3b. Hence,... 顯示更多 p. 9 1. Solve the following systems of equations by the method of substiution. a. {a+3b=18 3a+5b=34 b. {16w=5-4s 3s-8=8w+7 2. Solve the following systems of equations by the method of elimination. a. {5x-2y=6 3x+2y=10 b. {6x-y-4/3=10 y+3x-7/4=1 3. Solve a. {5x+6y=1 4/3 x-2y= 8/3 b. Hence, solve the system of equations {5/m + 6/n = 1 4/3m - 2/n = 8/3

最佳解答:

此文章來自奇摩知識+如有不便請留言告知

1a........................................................................................... a+3b=18..........(1) 3a+5b=34...........(2) from(1) a=18-3b............(3) put(3) into (2) 3(18-3b)+5b=34 54-9b+5b=34 -4b=-20 b=5..............(4) put(4) into(3) we have a=3 1b. ...................................................................................................... 16w=5-4s........(1) 3s-8=8w+7..........(2) from (1) w=(5-4s)/16........(3) put (3) into (2) 3s-8=8[(5-4s)/16] +7 3s-8 = 5/2 -2s+7 s=7/2........(4) put (4) into (3) we have w=-9/16 2a.................................................................................................. 5x-2y=6.......(1) 3x+2y=10..........(2) add (1) to (2) We have 8x = 16 x=2............(3) put (3) into either (1) or (2) We have y=2 2b. ............................................................................................... 6x-y-4/3=10......(1) y+3x-7/4=1.......(2) add (1) to (2) We have 9x = 145/12 x = 145/108.........(3) put (3) into either (1) or (2) We have y = -59/18 3a.................................................................................................. 5x+6y=1........(1) 4/3 x-2y= 8/3.........(2) multiply (2) by 3 then add (1) We have 9x = 9 x = 1...........(3) put (3) into either (1) or (2) We have y = -2/3 3b...................................................................................... 5/m + 6/n = 1 4/3m - 2/n = 8/3 By comparing the coefficients with 3a we have x=1/m y=1/n therefore m=1 n=-3/2

其他解答: