Toán Lớp 6: a) x – 73 = (-35) + 55
b) 20 -2^x-1 = 4
c) 5 chia hết x+2
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Toán Lớp 6: a) x – 73 = (-35) + 55
b) 20 -2^x-1 = 4
c) 5 chia hết x+2
Comments ( 2 )
@Mem gửi bạn
Xin hay nhất
x – 73 = 20
x = 20 + 73
x = 93
b) 20 – $2^{x-1}$ = 4
$2^{x-1}$ = 20 – 4
$2^{x-1}$ = 16
$2^{x-1}$ = $2^{3}$
x – 1 = 3
⇒ x = 4
⇒ ( x + 2 ) ∈ Ư(5)
Ư(5) = { 1;5 }
⇒ (x + 2) = {1 ; 5}
(x + 2) = 1 ⇒ x = -1 ( loại )
(x + 2) = 5 ⇒ x = 3 ( thỏa mãn )
Vậy x = 3