Question

 1 . Determinati numarul natural x pentru care x^2 + 3^4 = 15^2 . 

2 . Aflati toate numerele naturale de forma abc cu bara deasupra care au ultima cifra 0 sau 5 si a^2 = 9 . 

Answer 1

1. X² + 3 ∧4 = 15²
X² + 81 = 225
X² = 225 - 81
X² = 144
X = √144
X = 12
2. A² = 9⇒  A = √9   ⇒ A = 3
B = 1, 2, 3 , 4, 5, 6, 7, 8, 9, 0
C = 0, 5
ABC:   310, 320, 33, 340, 350, 360, 370, 380, 390, 300
           315, 325, 335, 345, ,355, 365, 375, 385, 395, 305
            

Answer 2

1)$x^{2} +3^{4}=15^{2}   x^{2}=15^{2}-3^{4}  x^{2}+225-81  x^{2}=141  x= \sqrt{144}   x=12$
2) $a^{2}=9=>a=\sqrt{9}$ => a =3 
$\frac{}{abc} =\frac{}{3bc}$$\frac{}{3b0}<=>b = 1,2,3,4,5,6,7,8,9,0$
$\frac{}{3b5} <=>b= 1,2,3,4,5,6,7,8,9,0$ $\frac{}{abc}={300, 310,320.. 390, 305.315...395}$