Răspuns:
Explicație pas cu pas:
A) 90*1=90+1-90=91-90=1
B) (x*y)*z= (x+y-90)*z=(x+y-90)+z-90=x+(y+z-90)-90=x*(y+z-90)=x*(y*z)
C) (x^2)*(2x+1)=-74
x^2 + (2x+1)-90=-74
x^2 +2x +1 -90 + 74=0
X^2 +2x -15=0
(x-3)(x+5)=0
x=3
X=-5
