Question

1) Calculati:
a) (x-1)²(x+1)-x²=x-1
b) (y+1)(y+2)+2y+1=y²+4y
c) (t+1)(t-2) -t(t-3)=1
d) z²-z-z(z+2)=3z-4

Answer 1

a)(x-1)²(x+1)-x²=x-1
(x²-2x+1)(x+1)-x²-x+1=0
x³-2x-2x²-2x+x+1-x²-x+1=0
x³-3x²-4x+2=0
x(x²-3x-4)=-2
xunu=-2
x²-3x-4=0
Δ=25
xdoi=3-5/2=-2/2=-1
x trei=3+5/2=8/2=4

B)(y+1)(y+2)+2y+1=y²+4y
y²+2y+y+2+2y+1-y²-4y=0
y+3=0
y=-3

c)(t+1)(t-2)-t(t-3)=1
t²-2t+t-2-t²+3t-1=0
2t-3=0
2t=3
t=3/2

d)z²-z-z(z+2)=3z-4
z²-z-z²-2z-3z+4=0
-6z+4=0
-2(3z-2)=0
3z-2=0
3z=2
z=2/3