Question

2x 3y - 7 =0 ;(a-1) x+(a+1) y =3 a - 1 find the value of a and b

Answer 1

where is bin the question.......

Answer 2

2x+3y-7=0 or, 
2x+3y=7                                     AND   (a-1)x+(a+1)y= 3a-1
So, 
here a1= 2, b1= 3 and c1=7
        a2= a-1, b2=a+1 and c2=3a-1
The condition for infinitely many solutions is : 
a1/a2=b1/b2=c1/c2

i.e.
=>  2/a-1=3/a+1=7/3a-1
=> 2/a-1=3/a+1
     (by doing cross multiplication), 
=>  2(a+1) = 3(a-1)
=>  2a+2 = 3a-3
=>  2a-3a+2+3 = 0
=>  -a+5=0
=>  -a=-5
=>  i.e. a=5