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matematyka klasa 7 strona 175 zadanie 2 a-d
a) (x + 1) (x + 2)
b) (3a+4) (a-5)
c) (2t+1)(1-3t)
d) (3ab-7) (3-7ab)


Odpowiedź :

a)

(x + 1)(x + 2) = x² + 2x + x + 2 =

= x² + 3x + 2

b)

(3a + 4)(a - 5) = 3a² - 15a + 4a - 20 =

= 3a² - 11a - 20

c)

(2t + 1)(1 - 3t) = 2t - 6t² + 1 - 3t =

= -6t² - t + 1

d)

(3ab - 7)(3 - 7ab) = 9ab - 21a²b² - 21 + 49ab =

= -21a²b² + 58ab - 21