Question

1. Efectuati:
a)2x*0,5y-0,3*5y+1,25x*y+0,5x*0,5 y
b)0,(5)a* 0,3 b + 0,5 a*1,(6)b-2,3*3ab+0,9 ab
c) (x la putera a doua - 2x +2 ) (x la puterea a doua-3x+1) +(x la puterea a doua+2x-1) ( x la puterea a doua +x+4)

Answer 1

a. xy-1,5y+1,25xy+0,25xy=
=2,5xy-1,5y=0,5y(5x-3)  (poate ca al doilea termen il continea si pe x?)

b. 5/9 · 3/10 ·ab+1/2·15/9·ab-6,9ab+0,9ab=
=1/3·1/2 ab+15/18 ab-6ab=
=3/18 ab+15/18 ab-6ab=
=18/18 ab - 6ab=ab-6ab=-5ab

c. (x²-2x+2)(x²-3x+1)+(x²+2x-1)(x²+x+4)= (inmultim fiecare cu fiecare din paranteze avand mare grija la semne)
=x^4-3x³+x²-2x³+6x²-2x+2x²-6x+2+
  x^4+x³+4x²+2x³+2x²+8x-x²-x-4=
=2x^4-2x³+14x²-x-2