Odpowiedź :
Odpowiedź:
15.
4s(4t - 3s) + 3t(2t + s) = 16st - 12s² + 6t² + 3st = -12s² + 19st + 6t²
16.
a)
x/4 = 5/9
9x = 20 /:9
x = 20/9 = 2 2/9
b)
(x - 2)/3 = x/4
1/3x - 2/3 = 1/4x
1/3x - 1/4x = 2/3
4/12x - 3/12x = 2/3
1/12x = 2/3 /*12
x = 2/3 * 12 = 8
Szczegółowe wyjaśnienie:
Zadanie 15
4s (4t - 3s) + 3t (2t + s)
16 st - 12s² + 6t² + 3st
-12s² + 6t² + 19 st
Zadanie 16
a) x/4 = 5/9
9x = 4 · 5
9x = 20 |: 9
x = 20/9 = 2 2/9
b) (x - 2)/3 = x/4
4(x -2) = 3x
4x - 8 = 3x
4x - 3x = 8
x = 8