Odpowiedź:
25.
4a = bc^2 /c^2
b = 4a/c^2
26.
66 + 6 = 72
72 * 6 = 432
432 - 6 = 426 /6 = 71
Pomyślał o 71.
27.
a)
5x = 2/9 /5
x = 2/9 * 1/5 = 2/45
b)
x + 1 = 4x/5 /*5
5x + 5 = 4x
5x - 4x = - 5
x = -5
28.
a) -3x + 5x = 1 + 7
2x = 8 /2
x = 4
b) 4x + 8 + 3 = 5 - 2x
4x + 2x = 5 - 11
6x = - 6/ 6
x = -1
29.
podstawa - x
ramię - 2x
Obwód = 2x + 2x + x = 45
5x = 45 /5
x = 9
30.
5m = (z + y) * x /x
5m/x = z + y
z = 5m/x - y
31.
a^2 + 4a + 4 - (a^2 - 6a + 9) = 5
a^2 + 4a + 4 - a^2 + 6^a - 9 = 5
10a - 5 = 5
10a = 10 /10
Przyjmuje taką wartość dla a = 5
32.
4x = 17,5 - x
5x = 17, 5 /5
x = 7/2
4x = 28/2 = 14
2x+5 = 4x - 2
4x - 2x = 5 + 2
2x = 7 /2
x = 7/2
2x + 5 = 7 + 5 = 12
Obwód = 2 * 14 + 2 * 12 = 28 + 25 = 52
33.
50 - 28 = 22
22/2 = 11 lat
34.
Wiek Jarka - x
x + x + 6 + 2*30 = 104
2x + 66 = 104
2x = 104 - 66 = 38 /2
x = 17 lat - wiek Jarka
x + 6 = 26 lat - wiek Radka
35.
x + x + 50 = 230
2x = 230 - 50 = 180 /2
x = 90 MB - pierwsza gra w MB
90 + 50 = 140 MB - druga gra w MB
36.
-2^3 - 2 + 6 = 0
-8 - 2 + 6 = -4 - fałsz
1/-5 = -0,2 - Prawdziwe
12x = 15 / 12
x = 15/12 = 5/4
3x - 3 = 2 - x
2x = 5 /2
x = 5/2 - Fałsz
37.
1/3x
2/3 * 1/4 = 2/12
4/12 + 2/12 = 6/12 x 12/12 - 6/12 = 6/12
6/12x = 18 / 6/12
x = 36 samochodów
38.
a) 5x = -12 /5
x = -12/5
b) 4/5 (2y - 1) = 2
8/5y - 4/5 = 2
8/5y = 2 + 4/5 = 14/5 /8/5
y = 7/4
c) 5z - 5 = 4z + 8
5z - 4z = 8 + 5
z = 13
