f) (2x+1)² - 3(x+3)(x-2) - (x+1)(x-8)
Folosim formula de calcul prescurtat: (a+b)² = a² + 2ab + b²
= 4x² + 4x + 1 + ( - 3x - 9 )(x+2) - ( x² -8x+x-8) =
Se inmultesc parantezele
= 4x² + 4x + 1 - 3x² + 6x - 9x + 18 - x² + 7x + 8 =
Se reduc termenii asemenea
= 0 + 4x + 1 + 6x - 9x + 18 + 7x + 8 =
= 0 + 8x + 1 + 18 + 8 =
= 0 + 8x + 27 = 8x+27