Tìm x,biết
a) 4 x3+15=47
b)4.2x -3 =125
tìm số tự nhiên x, biết a 4x3 15 47b 4.2x 3 125
Tìm x, biết:
a) 1230 : 3 ( x - 20 ) = 10
b) 250 - 10 ( 24 - 3 x ) : 15 = 244
c) 4 x 3 + 15 = 47
d) 65 - 4 x + 2 = 2014 0
e) 4 . 2 x - 3 = 125
Tìm x, biết:
a, 1230 : 3(x – 20) = 10
b, 250 – 10.(24 – 3x):15 = 244
c, 4 x 3 + 15 = 47
d, 65 - 4 x + 2 = 2014 0
e, 4 . 2 x - 3 = 125
a, 1230 : 3(x – 20) = 10
3(x – 20) = 123
x – 20 = 41
x = 61
b, 250 – 10.(24 – 3x):15 = 244
10.(24 – 3x):15 = 6
10.(24 – 3x) = 90
24 – 3x = 9
3x = 15
x = 5
c, 4 x 3 + 15 = 47
4 x 3 = 32
x 3 = 8 = 2 3
x = 2
d, 65 - 4 x + 2 = 2014 0
65 - 4 x + 2 = 1
4 x + 2 = 64 = 4 3
x + 2 = 3
x = 1
e, 4 . 2 x - 3 = 125
4 . 2 x = 128
2 x = 32 = 2 5
x = 5
Tìm x
4.2x-3=125
4xlũy thừa 3+15=47
Mk cần gấp
4.2^x-3=125
4.2^x = 125 + 3
4.2^x = 128
2^x = 128 : 4
2^x = 32
=> 2^x = 2^5
=> x = 5
Vậy x = 5
4x3+15=47=>4x3=32=>x3=8=>x3=23=>x=2
4.2^x-3=125
4.2^x = 125 + 3
4.2^x = 128
2^x = 128 : 4
2^x = 32
=> 2^x = 2^5
=> x = 5
Vậy x = 5
4x3+15=47=>4x3=32=>x3=8=>x3=23=>x=2
1)tìm x bt:
a)7.2x=56
b)(2x+1)3=9.81
c)x3=82
d)4.2x-3=1
e)2.3x=162
a)7.2x=56⇔2x=8⇔2x=23⇔x=3
b)(2x+1)3=9.81⇔(2x+1)3=93⇔2x+1=9⇔2x=8⇔x=4
c)x3=82⇔x3=26⇔x=22⇔x=4
d)4.2x-3=1⇔4.2x=4⇔2x=1⇔2x=20⇔x=0
e)2.3x=162⇔3x=81⇔3x=34⇔x=4
a)x-15=23+12
b)800:(x-12)=10
c)12.x+120=480
d)(-5).x3-600=25
e)2x+2+2x+1+4.2x=160
cảm ơn nhiều
a: =>x-15=20
hay x=35
c: =>12x=360
hay x=30
( (8x - 12) :4).33=36
4x3+15=47
4.2x-3=125
\(3^3=27;3^6=729\)
\(\left(8X-12\right):4=729:27\)
\(\left(8X-12\right):4=27\)
\(8X-12=27.4\)
\(8X-12=108\)
\(8X=108+12\)
\(8X=120\)
\(X=120:8\)
\(X=15\)
-[(8x - 12):4] .33=36
[(8x - 12):4] = 36:33
[(8x - 12):4] = 33
(8x - 12):4 = 27
8x - 12 = 27 x 4
8x - 12 = 108
8x = 108 + 12
8x = 120
x = 120 : 8
x = 15
-4x3+15=47
4x3 = 47-15
4x3 = 32
x3 = 32:4
x3 = 8
x = 2
-4.2x-3=125
4.2x = 125 + 3
4.2x = 128
2x = 128:4
2x = 32
x = 32:2
x = 16
\(4X^3=47-15\)
\(4X^3=32\)
\(\Rightarrow4X^3=2\)
Tìm số tự nhiên x, biết: 4.2x - 3 = 125
4.2x – 3 = 125
4.2x = 125 + 3
4.2x = 128
2x = 128 : 4
2x = 32
2x = 25
x = 5
Vậy x = 5
tìm x biết
a,-25+49x2=0
b,16x2-25(x-2)2
c,(3x-2)2-9(x+4)(x+4)=2
d,x3-6x2+12x-8=0
e,-27+27x-9x2+x3=0
a: 49x^2-25=0
=>(7x-5)(7x+5)=0
=>7x-5=0 hoặc 7x+5=0
=>x=5/7 hoặc x=-5/7
b: Đề thiếu vế phải rồi bạn
c: (3x-2)^2-9(x+4)(x-4)=2
=>9x^2-12x+4-9(x^2-16)=2
=>9x^2-12x+4-9x^2+144=2
=>-12x+148=2
=>-12x=-146
=>x=146/12=73/6
d: x^3-6x^2+12x-8=0
=>(x-2)^3=0
=>x-2=0
=>x=2
e: x^3-9x^2+27x-27=0
=>(x-3)^3=0
=>x-3=0
=>x=3
a) \(-25+49x^2=0\)
\(\Leftrightarrow49x^2-25=0\)
\(\Leftrightarrow\left(7x\right)^2-5^2=0\)
\(\Leftrightarrow\left(7x-5\right)\left(7x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}7x-5=0\\7x+5=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}7x=5\\7x=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{7}\\x=-\dfrac{5}{7}\end{matrix}\right.\)
b) \(16x^2-25\left(x-2\right)^2=0\)
\(\Leftrightarrow\left(4x\right)^2-\left[5\left(x-2\right)\right]^2=0\)
\(\Leftrightarrow\left(4x-5x+10\right)\left(4x+5x-10\right)=0\)
\(\Leftrightarrow\left(10-x\right)\left(9x-10\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}10-x=0\\9x=10\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=10\\x=\dfrac{10}{9}\end{matrix}\right.\)
c) \(\left(3x-2\right)^2-9\left(x+4\right)\left(x+4\right)=2\)
\(\Leftrightarrow9x^2-12x+4-9\left(x^2+8x+16\right)=2\)
\(\Leftrightarrow9x^2-12x+4-9x^2-72x-144=2\)
\(\Leftrightarrow-84x-140=2\)
\(\Leftrightarrow-84x=142\)
\(\Leftrightarrow x=-\dfrac{142}{84}\)
\(\Leftrightarrow x=-\dfrac{71}{42}\)
d) \(x^3-6x^2+12x-8=0\)
\(\Leftrightarrow x^3-3\cdot2\cdot x^2+3\cdot2^2\cdot x-2^3=0\)
\(\Leftrightarrow\left(x-2\right)^3=0\)
\(\Leftrightarrow x-2=0\)
\(\Leftrightarrow x=2\)
e) \(-27+27x-9x^2+x^3=0\)
\(\Leftrightarrow x^3-9x^2+27x-27=0\)
\(\Leftrightarrow\left(x-3\right)^3=0\)
\(\Leftrightarrow x-3=0\)
\(\Leftrightarrow x=3\)
Mình sửa lại câu c một chút nha:
c: (3x-2)^2-9(x+4)(x+4)=2
=>(3x-2)^2-9(x+4)^2=2
=>(3x-2)^2-(3x+12)^2=2
=>(3x-2-3x-12)(3x-2+3x+12)=2
=>-14*(6x+10)=2
=>6x+10=-1/7
=>6x=-71/7
=>x=-71/42
b1:So Sánh
a)53 và 35 b) (273) và 2712 c) 324 và 277
b2 tìm số tự nhiên x, biết
a)x3=216
b)3x + 15=18
`1a)5^3` và `3^5`
`5^3=125`
`3^5=243`
Vì `243>125` nên `3^5>5^3`
__
`c)3^24` và `27^7`
`27^7=(3^3)^7=3^21`
Vì `3^24>3^31` nên `3^24>27^7`
`2a)x^3=216`
`=>x^3=6^3`
`=>x=6`
__
`b)3^x+15=18`
`=>3^x=18-15`
`=>3^x=3`
`=>x=1`