Question

3x+4y=12 and 7x+2y=17 solve this by cross multiply method

Answer 1

3x+4y-12=0 and 7x+2y-17=0 are given eqns

Solving by x,y,1 cross multiplying method

in eqn 1 ---- x=3, y=4, c=-12
in eqn 2 ---- x=7, y=2, c=-17
     
                          x       y    1               
                       4    -12    3     4
                          X      X    X
                       2    -17    7     2
x/[(-17x4)-(-12x2)] = y/[(-12x7)-(-17x3)] = 1/[(3x2)-(7x4)]              
x/-68+24 = y/-84+51 = 1/6-28
x/-44 = y/-33 = 1/-22
x=-44/-22, y=-33/-22
x=4/2, y=3/2
therefore x=2, y=3/2