5x-7y=3/*-2 2x-3y=7/*5 ---------- -10x + 14y = -6 10x - 15y = 35 ----------------- -y = 29 y=-29 x= -47 4x-5y=5/*-3 6x-7y=9/*2 ------------------ -12x + 15y = -15 12x - 14y = 18 ----------------------- y= 3 x = 5 ad 2 a+b=223 a - b = 25 ------------- a = 223 - b 223 - b - b = 25 ----------------- a = 223 - b -2b = --198 -------------- a= 223 - b b = 99 --------------- a = 124 b = 99
1. 5x-7y=3 /*(-2) 2x-3y=7 /*5 -10x+14y=-6 10x-15y=35 ____________ -y=29 /*(-1) y=-29 y=-29 2x-3*(-29)=7 y=-29 2x=-80 /:2 y=-29 x=-40 _______________________________ 4x-5y=5 /*3 6x-7y=9 /*(-2) 12x-15y=15 -12x+14y=-18 ____________ -y=-3 /*(-1) y=3 y=3 4x-5*3=5 y=3 4x=20 /:4 y=3 x=5 ____________________________________________________ 2x+3y+18=0 3x+5y+29=0 2x+3y=-18 /*3 3x+5y=-29 /*(-2) 6x+9y=-54 -6x-10y=58 __________ -y=4 /*(-1) y=-4 y=4 2x+3*4=-18 y=4 2x=-30 /:2 y=4 x=-15 zad. 2 x - pierwsza liczba y - druga liczba x+y=223 x-y=23 x=223-y 223-y-y=23 x=223-y -2y=-200 /:(-2) x=223-y y=100 x=223-100 y=100 x=123 y=100 Odp. Pierwsza liczba to 123, a druga liczba to 100.
5x-7y=3 /×(-2) 2x-3y=7 /×5 -10x+14y=-6 10x-15y=35 -y=29 y=-29 2x=7-87 x=-40 4x-5y=5 /×3 6x-7y=9 /×(-2) 12x-15y=15 -12x+14y=-18 -y=-3 y=3 4x=5+15 x=5 2x+3y+18=0 /×3 3x+5y+29=0 /×(-2) 6x+9y=-54 -6x-10y=58 -y=4 y=-4 2x=-18+12 x=-3 x+y=223 x-y=25 2x=248 x=124 y=223-124 y=99
