a) {2x + 4y =0 {-2x - y = -1 --------------- + 3y=-1 y=-1/3 {2x + 4y =0 {-2x - y = -1 /*4 {2x + 4y =0 {-8x-4y=-4 --------------- + -6x=4 x= - 2/3 b) {k + l = 4 {-k + l = -3 -------------- + 2l=1 l=1/2 {k + l = 4 /*-1 {-k + l = -3 {-k -l = -4 {-k + l = -3 ---------------- + -2k=-7 k=7/2
{2x + 4y =0 + {-2x - y = -1 ----------------- 3y = -1 / ÷3 y = - 1÷3 {y = -1÷3 {2x + 4 × (-1÷3) = 0 {y = -1÷3 {2x - 4÷3 = 0 {y = -1÷3 {2x = -4÷3 {y = -1÷3 {x = -2÷3 {k + l = 4 {-k + l = -3 2l = 1 l = 1÷2 {l = 1÷2 {k + 1÷2 = 4 {l = 1÷2 {k = 3,5
{2x + 4y =0 {-2x - y = -1 3y = -1 /:3 y= -1/3 2x +4y= 0 2x + 4*(-1/3)=0 2x+ (-4/3)=0 2x= 4/3 /:2 x= 2/3 {k + l = 4 {-k + l = -3 2l= 1/:2 l = 1/2 k+l= 4 k+1/2=4 k=4-1/2 k= 3 i 1/2
