Explicație pas cu pas:
Observatie:
Utilizam formula:
(a+b)(c+d) = ac + ad + bc + bd
Tinem cont de regula semnelor:
(+) × (+) = (+)
(+) × (-) = (-)
(-) × (+) = (-)
a) (x+1)(x+2) = x² + 2x + x + 2 = x² + 3x + 2
b) (x-1)(x-2) = x² - 2x - x + 2 = x² - 3x + 2
c) (x +3)(x+4) = x² + 4x + 3x + 12 = x² + 7x + 12
d) (x-3)(x-4) = x² - 4x - 3x + 12 = x² - 7x + 12
e) (x+2)(x-6) = x² - 6x + 2x - 12 = x² - 4x - 12
f) (x-2)(x+6) = x² + 6x - 2x - 12 = x² + 4x - 12
g) (x+5)(x+8) = x² + 8x + 5x + 40 = x² + 13x + 40
h) (5x+1)(8x+1) = 40x² + 5x + 8x + 1 = 40x² + 13x + 1
i) (x+2)(2x+1) = 2x² + x + 4x + 2 = 2x² + 5x + 2
j) (3x-1)(x-3) = 3x² - 9x - x + 3 = 3x² - 10x + 3
k) (4x-3)(2x-5) = 8x² - 20x - 6x + 15 = 8x² - 26x + 15
l) (2x+7)( 3x-8) = 6x² - 16x + 21x - 56 = 6x² + 5x - 56
Succes!
#copaceibrainly
