dział ROZWIAZYWANIE ZADAN prosze o pomoc. dam naj. zadanie w załaczniku (9 a b c d.)

a) { 2x - 2y = 7 |*(-2) { 4x - 3y = 21 { -4x + 4y = -14 { 4x - 3y = 21 ----------------------- y= 7 { y=7 { 2x - 2y =7 { y=7 { 2x -14 = 7 |+14 {y=7 {2x=21 |:2 {y=7 {x= 10.5 b) {0.4x + 0.3y = 1.4 |*(-10) {0.1x + 3y = 2.3 {-4x -3y=-14 {0.1x + 3y = 2.3 ----------------------- -3.9x = -11.7 |:(-3.9) x= 3 {x=3 {0.1x+3y=2.3 {x=3 {y=2/3 c) {2x+3y=14 |*3 {3x-2y = 8 |*(-2) {6x+9y =42 {-6x+4y=-16 ------------------------ 13y=26 |:2 y=2 {y=2 {2x+3y=14 {y=2 [2x+6=14 |-6 {y=2 {2x=8 |:2 {y=2 {x=4 d) {1/2x-2y=8 |*(-4) {2x+5y =6 {-2x+8y=-32 {2x+5y=6 ----------------- 13y=-26 |:13 y=-2 {y=-2 {2x+5y=6 {y=-2 {2x-10=6 |+10 {y=-2 {2x=16|:2 {y=-2 {x=8