Question

am nevoie de ajutor, va rog

Answer 1

x*y = 4xy+4x+4y+3

a) inlocuiesti pe x cu 1 si pe y cu -1

1*(-1) = -4+4-4+3 = -4+3= -1

b) x*y = 4xy+4x+4y+3 = 4xy+4x+4y+(4-1) = 4x(y+1)+4(y+1) - 1 = (y+1)(4x+4)- 1 = 4(x+1)(y+1) - 1  

c) (x*1/4)* (-x) = 19

x*1/4 = 4x*1/4 + 4x+4*1/4 + 3 = x+4x+1+3 = 5x+4

(5x+4)*(-x) = 4(5x+4)(-x) + 4(5x+4) -4x+3 = (20x+16)(-x)  +20x+16-4x+3 = -20x²-16x+16x+13 = -20x²+13

-20x²+13 = 19

-20x² = 6

-x² = 6/20 = 3/10

x² = -3/10

x = -V(3/10) = -V3/V10 rationalizezi cu V10

x = -V30/10