Question

Se considera numerele : x=√162 - √242 +√288 - √98+√18 si y = √320+√20-√500 +√125 -√180
a ) Calculati x si y
b) Incardrati numarul x intre doua numere naturale consecutive
c) Aratati ca x·y apartine intervalului (-19 ; -18 )

Answer 1

a) x = 9√2 - 11√2 + 12√2 - 7√2 + 3√2 = 6√2
y = 8√5 + 2√5 - 10√5 + 5√5 - 6√5  = -√5

b)  8 < x < 9

c) 6√2 x (-√5) = -6√10 
√10 > √9 = 3
6√10 > 18
-6√10 < -18

Verificam ca:
-6√10 > -19
6√10 < 19
360 < 361 adevarat