2.3x+14=20
Tìm số tự nhiên x biết
a) (19x + 2.52):14 = (13 – 8)2 – 42
b) 2.3x = 10.312 + 8.274
help meeeeeeeeeeee
a, ( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 42
( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 16
( 19x + 2.52 ) : 14 = 52 - 16
( 19x + 2.52 ) : 14 = 25 - 16
( 19x + 2.52 ) : 14 = 9
( 19x + 2.25 ) : 14 = 9
( 19x + 2.25 ) = 9 . 14
( 19x + 2.25 ) = 126
( 19x + 50 ) = 126
19x = 126 - 50
19x = 76
x = 76 : 19
x = 4
Vậy x = 4
b, 2 . 3x = 10 . 312 + 8 . 274
2 . 3x = 10 . 274 + 8 . 274
2 . 3x = 274 . ( 10+8 )
2 . 3x = 274 . 18
2 . 3x = 9565938
3x = 9565938 : 2
3x = 4782969
3x = 314
=> x = 14
Vậy x = 14
Đây nha bạn!!!
Chúc bạn học tốt!!!
a, ( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 42
( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 16
( 19x + 2.52 ) : 14 = 52 - 16
( 19x + 2.52 ) : 14 = 25 - 16
( 19x + 2.52 ) : 14 = 9
( 19x + 2.25 ) : 14 = 9
( 19x + 2.25 ) = 9 . 14
( 19x + 2.25 ) = 126
( 19x + 50 ) = 126
19x = 126 - 50
19x = 76
x = 76 : 19
x = 4
Vậy x = 4
b, 2 . 3x = 10 . 312 + 8 . 274
2 . 3x = 10 . 274 + 8 . 274
2 . 3x = 274 . ( 10+8 )
2 . 3x = 274 . 18
2 . 3x = 9565938
3x = 9565938 : 2
3x = 4782969
3x = 314
=> x = 14
Vậy x = 14
Tìm số tự nhiên x biết
a) (19x + 2.52):14 = (13 – 8)2 – 42
b) 2.3x = 10.312 + 8.27
ai rảnh giúp mk với nhé
a) \(\left(19x-2.52\right):14=\left(13-8\right).2-42\)
\(\left(19x-50\right):14=10-42\)
\(\left(19x-50\right):14=-32\)
\(19x-50=-448\)
\(19x=-398\)
\(x=-\dfrac{398}{19}\)
Tính:
\(\frac{1}{14}+\frac{1}{35}+\frac{1}{65}+...+\frac{2}{x^2.3x}=\frac{1}{9}\)
a. Tìm các chữ số a,b biết rằng số \(\overline{a1984b}\) là một bội số của 45.
b. Tìm X \(\in\) N sao cho 3x +2.3x-2 =297
c. Tính A=\(\dfrac{6^{14}+2^{14}.9^8}{12.8^4.3^{12}}\)
b: Ta có: \(3^x+2\cdot3^{x-2}=297\)
\(\Leftrightarrow3^x=297:\dfrac{11}{9}=243\)
hay x=5
Tìm x, biết:
\(\frac{10^{10}+10^{11}+10^{12}}{13^2+14^2\left(2.3x^{-5}-2^3.3^2\right)}=2.5^2.5\)
4x+2.3x=16.125
`4^(x+2) .3^x = 16.12^5`
`4^(x+2) .3^x = 4^2 . (3.4)^5`
`4^(x+2) .3^x = 4^2 . 3^5. 4^5`
`4^(x+2) .3^x = 4^7 . 3^5`
`4^(x+2) .3^x = 4^(5+2) . 3^5`
`x=5`
Ta có:4x+2.3x=16.125
⇔ 4x+2.3x=417.315
⇔ 4x+2:417.3x:315=1
⇔ 4x-15.3x-15=1
⇔ 12x-15=120
⇔ x-15=0
⇔ x=15
Ta có: \(4^{x+2}\cdot3^x=16\cdot12^5\)
\(\Leftrightarrow4^x\cdot16\cdot3^x=16\cdot12^5\)
\(\Leftrightarrow12^x=12^5\)
hay x=5
2.3x=10.312+8.274
\(2.3^x=10.3^{12}+8.\left(3^3\right)^4\)
\(2.3^x=10.3^{12}+8.3^{12}\)
\(2.3^x=3^{12}.\left(10+8\right)\)
\(2.3^x=3^{12}.18\)
\(3^x=3^{12}.18:2\)
\(3^x=3^{12}.9\)
\(3^x=3^{12}.3^2\)
\(3^x=3^{14}\)
\(\Rightarrow x=14\)
2.3x=10.312+8.274
2.3x=10.312+23.312
2.3x=312.18
2.3x=312.32.2
2.3x=314.2
=>x=14
2.3x+3=10.312 + 8.312
\(2.3^{x+3}=10.3^{12}+8.3^{12}\)
\(\Leftrightarrow2.3^{x+3}=18.3^{12}\)
\(\Leftrightarrow3^{x+3}=9.3^{12}\)
\(\Leftrightarrow3^{x+3}=3^{14}\)
\(\Leftrightarrow x+3=14\Leftrightarrow x=11\)
\(\Leftrightarrow2\cdot3^{x+3}=3^{12}\cdot18\\ \Leftrightarrow2\cdot3^{x+3}=3^{14}\cdot2\\ \Leftrightarrow x+3=14\Leftrightarrow x=11\)
2.3x+3=10.312+8.3122.3x+3=10.312+8.312
=2.3x+3=18.312⇔2.3x+3=18.312
=3x+3=9.312⇔3x+3=9.312
=3x+3=314⇔3x+3=314
=x+3=14⇔x=11
2.3x + 5.3x + 1 = 153
\(2.3^x+5.3^x.3=153\Leftrightarrow2.3^x+15.3^x=153\)
\(\Leftrightarrow17.3^x=153\Leftrightarrow3^x=9\Leftrightarrow x=2\)
\(\Leftrightarrow2.3^x+5.3.3^x=153\)
\(\Leftrightarrow17.3^x=3^2.17\)
\(\Leftrightarrow3^x=3^2\Rightarrow x=2\)
2.3x=10.312+8.274
mình thêm nhé
2.3x=10.312+8.274
2.3x=10.312+23.312
2.3x=312.18
2.3x=312.32.2
2.3x=314.2
=>x=14