(x+5)3-x3-125
Tìm x
x3+125+(x+5)(x-25)=0
\(x^3\) + 125 + (\(x\) + 5)(\(x\) - 25) = 0
(\(x^3\) + 53) + (\(x\) + 5)(\(x\) - 25) = 0
(\(x\) + 5)(\(x^2\) - 5\(x\) + 25) + (\(x\) + 5)(\(x\) - 25) =0
(\(x\) + 5)(\(x^2\) - 5\(x\) + 25 + \(x\) - 25) = 0
(\(x\) + 5)(\(x^2\) - 4\(x\)) = 0
\(x\)(\(x\) + 5)(\(x\) - 4) = 0
\(\left[{}\begin{matrix}x=0\\x+5=0\\x-4=0\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=0\\x=-5\\x=4\end{matrix}\right.\)
`x^3 + 125 + (x + 5)(x - 25) = 0`
`<=>(x + 5)(x^2 + 5x + 25) + (x + 5)(x - 25) = 0`
`<=>(x + 5)(x^2 + 6x) = 0`
`<=>x(x + 5)(x + 6) = 0`
`<=>x = 0` hoặc `x = -5` hoặc `x=-6`
Sửa:
`x^3 + 125 + (x + 5)(x - 25) = 0`
`<=>(x + 5)(x^2 - 5x + 25) + (x + 5)(x - 25) = 0`
`<=>(x+5)(x^2-4x)=0`
`<=>x(x+5)(x-4)=0`
`<=>x=0` hoặc `x=-5` hoặc `x=4`
tìm x (x thuộc n)
a) 5x=125
b) 32x=81
c) 52x-3-2x52=52x3
a) 5^x=125
=> 5^x=5^2
=>x=2
b) 3^2*x=81
=>3^2*x=9^2
=>3^2*x=(3^2)^2
=>x=2
câu c chưa hiểu chỗ 5^2x3 hay 5^2*3 vậy ?
a) \(5^x=125\)
\(5^x=5^3\)
\(\Rightarrow x=3\)
b)\(3^{2x}=81\)
\(3^{2x}=3^4\)
\(\Rightarrow2x=4\)
\(x=4:2\)
\(x=2\)
c)\(5^{2x-3}-2.5^2=5^2.3\)
\(5^{2x-3}=5^2.3+5^2.2\)
\(5^{2x-3}=5^2.\left(3+2\right)\)
\(5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\)
\(2x=3+3\)
\(2x=6\)
\(x=6:2\)
\(x=3\)
Tìm x biết:
a) 27x3-54x2+36x-8=0
b) x3+15x2+75x+125=0
c) x3-18x2+108x-216=0
d) (x-1)3-x.(x2+3x)=2
e) (x+1)3+(x-2)3-2x2.(x-1,5)=3
Giải chi tiết giúp mình nha.Cảm ơn nhiều
tính giá trị biểu thức sau:
a) 54 +22 x 52-125
23x3
(x-6)2=9
5x+1=125
52x3-2x52=52x3
1/\(\left(x-6\right)^2=9\Rightarrow\orbr{\begin{cases}x-6=-3\\x-6=3\end{cases}\Rightarrow\orbr{\begin{cases}x=3\\x=9\end{cases}}}\)
2/\(5^{x+1}=125\Leftrightarrow5^{x+1}=5^3\Rightarrow x+1=3\Rightarrow x=2\)
3/ đề thiếu
1. Tìm x
A, 3^x+2 +3^x = 810
B, 2^x3 - 2^ x
C, 5^x+1 +5^x -2 =126
2 . So sánh
A, 27^11 và 81^8
B, 5^36 và 11^24
C, 625^5 và 125^7
Bài 1:
a: \(\Leftrightarrow3^x\cdot10=810\)
\(\Leftrightarrow3^x=81\)
hay x=4
c: \(\Leftrightarrow5^x\cdot5+5^x\cdot\dfrac{1}{25}=126\)
\(\Leftrightarrow5^x\cdot\dfrac{126}{25}=126\)
\(\Leftrightarrow5^x=25\)
hay x=2
Bài 2:
a: \(27^{11}=3^{33}\)
\(81^8=3^{32}\)
mà 33>32
nên \(27^{11}>81^8\)
c: \(625^5=\left(5^4\right)^5=5^{20}\)
\(125^7=\left(5^3\right)^7=5^{21}\)
mà 20<21
nên \(625^5< 125^7\)
tinh 212x35-46x272 phan (23x3)6+44x35 - 510x73-255x492 phan (125x7)3+1253x75
tinh 212x35-46x272 phan (22x3)6+44x35 - 510x73-255x492 phan (125x7)3+1253x75
tinh 212x35-46x272 phan (22x3)6+44x35 - 510x73-255x492 phan (125x7)3+1253x75
rút gọn phân thức
1 . 8x3-125 / 3(x-3)-(x-3)(8-4x)
2 . x4-y4 / y3-x3
3 . x10-x8-x7-x6-x5-x4-x3-x2+1 / x30+x24+x18+x12+x6+1
2: \(=\dfrac{\left(x-y\right)\left(x+y\right)\left(x^2+y^2\right)}{-\left(x-y\right)\left(x^2+xy+y^2\right)}=\dfrac{-\left(x+y\right)\left(x^2+y^2\right)}{x^2+xy+y^2}\)