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\(a,TH1:x-2021=0=>x=2021\)
\(Th2:x-2022=0=>x=2022\)
Vậy \(x\in\left\{2021;2022\right\}\)
\(b,x\left(8-5\right)=1080\)
\(x.3=1080\)
\(x=360\)
\(c,x^3=216< =>6^3=216=>x=3\)
\(d,5^5=3125\)
a) ( x- 2021) * ( x- 2022) = 0
=> \(\orbr{\begin{cases}x-2021=0\\x-2022=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=2021\\x=2022\end{cases}}}\)
b) b. 8x - 5x = 2022
=> 3x = 2022
=> x = 674
c) \(5\cdot x^3=1080\)
=> \(x^3=216\)
=> \(x^3=6^3\)
=> x = 6
d) \(5^x=3125\)
=> \(5^x=5^5\)
=> x = 5
i don't now
mong thông cảm !
...........................
\(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}\)
ta có :
\(\frac{1}{2^2}< \frac{1}{1\cdot2}\)
\(\frac{1}{3^2}< \frac{1}{2\cdot3}\)
\(\frac{1}{4^2}< \frac{1}{3\cdot4}\)
...
\(\frac{1}{100^2}< \frac{1}{99\cdot100}\)
nên \(A< \frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{99\cdot100}\)
\(\Rightarrow A< 1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)
\(\Rightarrow A< 1-\frac{1}{100}\)
\(\Rightarrow A< \frac{99}{100}< 1\)
\(\Rightarrow A< 1\left(đpcm\right)\)
nhiều qá lm sao nổi
a) \(a^2\cdot a^3\cdot a^7\cdot b^2\cdot b\)
\(=\left(a^2\cdot a^3\cdot a^7\right)\cdot\left(b^2\cdot b\right)\)
\(=a^{12}\cdot b^3\)
b) \(b^6\cdot b\cdot c^7\cdot c^8\)
\(=\left(b^6\cdot b\right)\cdot\left(c^7\cdot c^8\right)\)
\(=b^7\cdot c^{15}\)
c) \(a^8\cdot a^9\cdot a\cdot c\cdot c^{20}\)
\(=\left(a^8\cdot a^9\cdot a\right)\cdot\left(c\cdot c^{20}\right)\)
\(=a^{18}\cdot c^{21}\)
d) \(a^2\cdot a^3\cdot b^4\cdot c\cdot c^3\)
\(=\left(a^2\cdot a^3\right)\cdot b^4\cdot\left(c\cdot c^3\right)\)
\(=a^5\cdot b^4\cdot c^4\)
a) Kiểm tra lại nhé
b) \(b^6.b^7.c^8\)
\(=b^{6+7}.c^8=b^{13}.c^8\)
c) \(a^8.a^9.a.c.c^{20}\)
\(=a^{8+9+1}.c^{1+20}\)
\(=a^{18}.c^{21}\)
d) \(a^2.a^3.b^4.c.c^3\)
\(=a^{2+3}.b^4.c^{1+3}\)
\(=a^5.b^4.c^4\)
\(#WendyDang\)
\(a,=4\cdot3-\left(1+1\right):2=12-2:2=12-1=11\\ b,=\left[47-\left(736:2^4\right)\right]\cdot2013=\left(47-736:16\right)\cdot2013=\left(47-46\right)\cdot2013=2013\)
a, \(2n+5⋮n-1\)
\(2\left(n-1\right)+7⋮n-1\)
\(7⋮n-1\)hay \(n-1\inƯ\left(7\right)=\left\{\pm1;\pm7\right\}\)
n - 1 | 1 | -1 | 7 | -7 |
n | 2 | 0 | 8 | -6 |
b, Công thức tổng quát : \(A\left(x\right).B\left(x\right)=0\Rightarrow\orbr{\begin{cases}A\left(x\right)=0\\B\left(x\right)=0\end{cases}}\)
\(\left(2n+3\right)\left(n-4\right)=0\Leftrightarrow\orbr{\begin{cases}n=-\frac{3}{2}\\n=4\end{cases}}\)
c, \(\left|x-3\right|< 3\Leftrightarrow-3< x-3< 3\)
\(\Leftrightarrow-3+3< x< 3+3\Leftrightarrow0< x< 6\)
Vậy \(x\in\left\{1;2;3;4;5;\right\}\)
a) \(\left(2x+1\right)^3=27\)
\(\Leftrightarrow2x+1=3\)
\(\Leftrightarrow x=1\)
b) \(\left(2x-1\right)^3=125\)
\(\Leftrightarrow2x-1=5\)
\(\Leftrightarrow x=3\)
c) \(\left(x+1\right)^4=\left(2x\right)^4\)
\(\Leftrightarrow x+1=2x\)
\(\Leftrightarrow x=1\)
d) \(\left(2x-1\right)^5=x^5\)
\(\Leftrightarrow2x-1=x\)
\(\Leftrightarrow x=1\)
a. ( 2x + 1 )3 = 27
<=> ( 2x + 1 )3 = 33
<=> 2x + 1 = 3
<=> 2x = 2
<=> x = 1
b. ( 2x - 1 )3 = 125
<=> ( 2x - 1 )3 = 53
<=> 2x - 1 = 5
<=> 2x = 6
<=> x = 3
c. ( x + 1 )4 = 2x4
<=> x + 1 = 2x
<=> x = 1
d. ( 2x - 1 )5 = x5
<=> 2x - 1 = x
<=> x = 1
{47 - [736 : (5 - 3)4]} x 2013
= {47 - [736 : 24]} x 2013
= {47 - [736 : 16]} x 2013
= {47 - 46} x 2013
= 1 x 2013
= 2013