Rozwiąż układy równań metoda przeciwnych współczynników . a) {x+1/2y=6.5 {2x-y=3 b) {1/4x+3/20y=1.5 {x+0.3y=6

a) {x + 1/2y = 6.5 | *2 {2x - y = 3 {2x + y = 13 {2x - y = 3 4x = 16 | :4 x = 4 2x +y = 13 y = 13 - 2x = 13 - 2*4 = 13 - 8 = 5 b) {1/4x + 3/20y = 1.5 {x + 0.3y = 6 {0.25x + 0.15y = 1.5 | * (-2) {x + 0.3y = 6 {-0.5x - 0.3y = -3 {x + 0.3y = 6 0.5x = 3 | *2 x = 6 0.25x + 0.15y = 1.5 0.15y = 1.5 - 0.25x |*6 y = 9 - 1.5x y = 9 - 1.5*6 = 9 - 9 = 0