Question

calculati! 1.(x-1)(x+2);2.(x+2)la patrat;3.(1-x)la patrat;4.(x-y)(x+y);5.(x+y-z)(x+y+z)6.(2supra3+5)x-8x;9.x-1supra3-x+2supra2.va rog mult ajutatima

Answer 1

(x-1)(x-2)= x^2 -2x -x +2= x^2 -3x +2
(x+2)^2 = x^2 + 2*x*2+ 2^2= x^2 + 4x+ 4
(x+y-z)(x+y+z) = dupa formula (a-b)(a+b)=a^2-b^2 si consideram x+y=a si z=b =
                      = (x+y)^2 - z^2 = x^2 + 2xy + y^2 - z^2
(2/3+5)x - 8x= 2x/3 +5x-8x= 2x/3 -3x= (2x-9x) /3= - 7x/3
(x-1)/3 - (x+2)/2 = (2x-2-3x-6) /6= - (x+8)/ 6