- Xin ctlhn
Bài 46 :
a) 2x + 12 = 44
⇒ 2x = 32
⇒ x = 16
Vậy x = 16
b) 2. $5^x+1$ - 1100 = 6. 5²
⇒ 2. $5^x+1$ - 1100 = 150
⇒ 2. $5^x+1$ = 1250
⇒ $5^x+1$ = 625
⇒ $5^x+1$ = $5^4$
⇒ x + 1 = 4
⇒ x = 3
Vậy x = 3
c) 2. $3^x+1$ = 10. $3^12$ + 8. $3^12$
⇒ 2. $3^x+1$ = $3^12$. ( 10 + 8 )
⇒ 2. $3^x+1$ = $3^12$. 18
⇒ 2. $3^x+1$ = $3^12$. 3² . 2
⇒ $3^x+1$ = $3^14$
⇒ x + 1 = 14
⇒ x = 13
Vậy x = 13
d) $2^x$ + $2^x+3$ = 144
⇒ $2^x$ + $2^x$. 2³ = 144
⇒ $2^x$. ( 1 + 8 ) = 144
⇒ $2^x$. 9 = 144
⇒ $2^x$ = 16
⇒ x = 4
Vậy x = 4
Bài 47 :
a) $7^4$. $7^6$. $7^6$ = $7^16$
b) $( 54 : 3 )^7$ . 324 = $18^7$. $3^4$. $2^2$ = $3^14$. $2^7$. $3^4$. $2^2$ = $3^18$. $2^9$ = $9^9$. $2^9$ = $18^9$
c)
( 8 + 2 )² . $10^100$ : ( $10^0$ : $10^94$ )
= $10^2$. $10^100$ . $10^94$
= $10^196$
