a)3x+12
x-y=1
x=12÷3
x=4
4-y=1
-y=1-4
-y=-3/x-1
y=3
b) 5y=2
x=y=2 2/5
x=2 2/5
y=2 2/5
c)4y-x=6
17y=0
y=0÷17
y=0
4x0-x=6
-x=6
x=-6
d)a=b
2a+b=9
b=9-2a
a=9-2a
a +2a=9
3a=9
a=3
b=3
e)u=4v
5u-v=10
5x4v - v=10
20v-v=10
19v=10
v=10/19
u=4 x 10/19
u=40/19
u=2 i 2/19
f) 3r=s
3r+s=24
3r+3r=24
6r=24
r=3
s=3 x3
s=9
ozwiąż układy równań metodą podstawiania .
a)
x + 3y = 3
x - y = 5
x + 3y = 3
x = 5 + y
5 + y + 3y = 3
x = 5 + y
4y = -2 /: 4
x = 5 + y
y = -1/2
x = 5 -1/2
y = -1/2
x = 4i 1/2
b)
2x - y = 10
x + 5y = - 17
x = - 17 - 5y
2 (- 17 - 5y) - y = 10
x = - 17 - 5y
-34 -10y -y = 10
x = - 17 - 5y
-11y = 44 /: -11
x = - 17 - 5y
y = 4
x = - 17 - 5 * 4
y = 4
x = - 37
y = 4
c)
3m + n = 9
2m - 5n = - 11
n = 9 - 3m
2m - 5 (9 - 3m) = -11
n = 9 - 3m
2m -45 + 15m = -11
n = 9 - 3m
17m = 34 / : 17
n = 9 - 3m
m = 2
n = 9 - 3 * 2
m = 2
n = 3
m = 2
d)
4a - 2 = b
3a + 7(4a - 2) = 1,5
b = 4a - 2
3a + 28a -14 = 1,5
b = 4a - 2
31a = 15,5 /:31
b = 4a - 2
a = 0,5
b = 4 * 0,5 - 2
a = 0,5
b = 4
a = 0,5
e)
5x = 4 - 2y
4x + y = 3
5x = 4 - 2y
y = 3 - 4x
5x = 4 - 2(3 - 4x)
y = 3 - 4x
5x = 4 - 6 + 8x
y = 3 - 4x
5 x - 8x = -2
y = 3 - 4x
-3x = -2 /: (-3)
y = 3 - 4x
x = 2/3
y = 3 - 4 * 2/3
x = 2/3
y = 1/3
f)
6x - 3y = 9
x + 5y = - 9,5
-3y = 9 - 6x /:-3
x + 5y = - 9,5
y = -3 + 2x
x + 5(-3 + 2x) = - 9,5
y = -3 + 2x
x - 15 + 10x = -9,5
y = -3 + 2x
9x = 5,5 / : 9
y = -3 + 2x
x = 5 i 1/2 : 9
y = -3 + 2x
x = 11/2 * 1/9
y = -3 + 2x
x = 11/18
y = -3 + 2 * 11/18
x = 11/18
y = -3 + 11/9
x = 11/18
y= -1 i 7/9
x = 11/18
-33y = 48
x = -9,5 -5y