解方程组：（1）x/3+y/7=7 （2） 2x-7y=3x-8y-2=8 x/2-y/3=-11）x/3+y/7=7 x/2-y_数学解答

解方程组：（1）x/3+y/7=7 （2） 2x-7y=3x-8y-2=8 x/2-y/3=-1
1）x/3+y/7=7
x/2-y/3=-1
2） 2x-7y=3x-8y-2=8

人气：275 ℃　时间：2020-04-30 10:16:05

解答

1）X/3 +Y/7 = 7 ==> X + 3Y/7 = 21X/2 - Y/3 = -1 ==> X - 2Y/3 = -2(3/7+2/3)Y =23 => Y= 21随便找个式子带进去 X= 122) 2X-7Y=3X-8Y-2 => X-Y=2 => 2X-2Y=4和2X-7Y=8 两边相减 5Y = -4 => Y=-4/5X = Y+2 = 6/5...