Question

[Khánh Linh]

Câu 3 :Tìm x biết:

a) ( x + 3 ) : 4 = 12

b) 5\(^{2015}\) : x = 5\(^{2013}\)

c) 21 + 3 . ( x - 7) = 72

Answer 1

[♥ Dora Tora ♥]

a) \(\left(x+3\right):4=12\)

\(x+3=12\cdot4\)

\(x+3=48\)

\(\Rightarrow x=45\)

b) 5²⁰¹⁵ : x = 5²⁰¹³

=> x = 5²⁰¹⁵ : 5²⁰¹³

=> x = 5²

c) 21 + 3 . ( x - 7 ) = 72

3 . ( x - 7 ) = 72 - 21

3 . ( x - 7 ) = 51

x - 7 = 51 : 3

x - 7 = 17

=> x = 24