119
a) 3x = 72 /:3
x = 24
b) [tex]\frac{x}{2} = 5[/tex] /*2
x = 10
c) 1 + 4x = 2
4x = 2 - 1
4x = 1 /:4
x = [tex]\frac{1}{4}[/tex]
d) 15 - 2x = -3
-2x = -3 - 15
-2x = -18 /:(-2)
x = 9
120
a) [tex]\frac{x+1}{3}[/tex] = 7 /*3
x + 1 = 21
x = 21 - 1
x = 20
b) [tex]\frac{3-x}{2} = \frac{1}{3}[/tex] /*6
3 (3 - x) = 2 * 1
9 - 3x = 2
-3x = 2 - 9
-3x = -7 /:(-3)
x= [tex]\frac{7}{3} = 2\frac{1}{3}[/tex]
c) 1 - 3x = [tex]\frac{1}{2}[/tex] /*2
2 - 6x = 1
-6x = 1 - 2
-6x = -1 /: (-6)
x = [tex]\frac{1}{6}[/tex]
d) [tex]\frac{1}{2}x[/tex] + 1 = 4 /*2
x + 2 = 8
x = 8 - 2
x = 6
121
a) 2x - 5 - x - 3 = 8
x - 8 = 8
x = 8 + 8
x = 16
b) 6 - x - [tex]\frac{x}{2}[/tex] = 4 /*2
12 - 2x - x = 8
-2x - x = 8 - 12
-3x = -4 /:(-3)
x = [tex]\frac{4}{3} = 1\frac{1}{3}[/tex]
c) [tex]\frac{3}{4}x[/tex] - x - 1 = 0 /*4
3x - 4x - 4 = 0
3x - 4x = 0 + 4
-x = 4 /:(-1)
x = -4
d) [tex]\frac{1}{5}x + 3 = 5 - \frac {1}{2}x[/tex] /*10
2*1x + 30 = 50 - 5*1x
2x + 30 = 50 - 5x
2x + 5x = 50 - 30
7x = 20 /:7
x = [tex]\frac{20}{7}= 2\frac{6}{7}[/tex]
122
Wzór na obwód prostokąta = 2b + 2a
Pod b podstawmy 7, a pod a podstawmy x
a więc:
2*7 + 2x = 22
14 + 2x = 22
2x = 22 - 14
2x = 8 /:2
x = 4
Odp. Długość boku x prostokąta wynosi 4.
