tìm x ∈ Z biết :
a , 2x – 15 = 3^5 : 3^3
b, 16 . 4^x = 4^8
c, | x + = 5
d, – 129 – ( 35 – x ) = 55
tìm x ∈ Z biết : a , 2x – 15 = 3^5 : 3^3 b, 16 . 4^x = 4^8 c, | x + = 5 d, – 129 – ( 35 – x ) = 55
By Harper
By Harper
tìm x ∈ Z biết :
a , 2x – 15 = 3^5 : 3^3
b, 16 . 4^x = 4^8
c, | x + = 5
d, – 129 – ( 35 – x ) = 55
Đáp án:
a)2x – 15 = $3^{5}$ :$3^{3}$
2x – 15 = $3^{2}$ =9
2x =9 + 15=24
x = 24:2=12
b)16 . 4^x = 4^8
$4^{2}$.$4^{x}$ =$4^{8}$
$4^{x}$ =$4^{8}$ :$4^{2}$
$4^{x}$ =$4^{6}$
x = 6
d)- 129 – ( 35 – x ) = 55
– 129 – 35 +x = 55
-35 + x = 55 + 129= 184
x = 184 + 35=219
a , 2x – 15 = 3^5 : 3^3
2x – 15 = 3^2
2x = 9 + 15
2x = 24
x = 24 : 2 = 12
b, 16 . 4^x = 4^8
4^2 . 4^x = 4^8
4^x = 4^8 : 4^2
4^x = 4^6
x = 6
d, – 129 – ( 35 – x ) = 55
( 35 – x ) = (-129 – 55)
( 35 – x ) = (-184)
x = (-184+35)
x = -149