a) E(x) = (x+5)² +2(x+5)(x-4) + (x-4)²
E(x) = x²+10x+25 + (2x+10)(x-4) + x²-8x+16
E(x) = 2x²+2x+41 +2x²-8x+10x-40
E(x) = 4x²+4x+1
E(x) = (2x+1)²
b) E(V2) = (2V2+1)² = 4*2+4V2+1 = 9+4V2
E(-V2) = (-2V2+1)² = (1-2V2)² = 1-4V2 + 4*2 = 9-4V2
(9+4V2) *(9-4V2) = 9² - (4V2)² = 81 - (16*2 ) = 81-32 = 49
c) E(a) = (2a+1)²
Pentru orice numar real a, (2a+1)² il egalam cu 0
(2a+1)² = 0 ridici totul la puterea a 2
2a+1 =0
2a = -1
a = -1/2
