1/7x-x=(-3)/5mu2
3mu4 .5mu2 -128.2mu3 +1 mu 17
24-4mu2:4.2+ 3
`@` `\text {Ans}`
`\downarrow`
`3^4*5^2 - 128*2^3 + 1^17`
`= 9^2*5^2 - 2^7*2^3 + 1`
`= (9*5)^2 - 2^10+1`
`= 45^5-2^10 + 1`
`= 2025 - 1024 + 1`
`= 2025 - 1023`
`= 1002`
\(24-4^2\div4\cdot2+3\)
`= 24 - 4*2 + 3`
`= 24 - 8 + 3`
`= 24 - 5`
`= 19`
`@` `\text {Kaizuu lv u}.`
D=4×5mu100×(1/5+1/5mu2+...+1/5mu100)+1
\(D=4\times5^{100}\times\left[\left(\frac{1}{5}\right)\left(\frac{1}{5}\right)^2\left(\frac{1}{5}\right)^3...\left(\frac{1}{5}\right)^{100}\right]+1\)
\(=4\times5^{100}\times\frac{1}{5\times5^2\times...\times5^{100}}+1\)
\(=\frac{4}{5\times5^2\times...\times5^{99}}+1\)
\(=\frac{4}{5^{99\left(1+99\right):2}}+1=\frac{4}{5^{4950}}+1\)
cho Q = 1/5 - 2/5mu2 +3/5mu3- 4/5mu4+.... +2021/5mu2021 - 2022/5mu2022 . so sanh Q voi 5/36
bài 25.Tìm số tự nhiên x,biết :
a,(18x+3.5.5):15=(14-8)mux2 - 5mu2
A=1+5+5mu2+5mu3...+5mu10+5mu11chia het ch 6 va31
A=(5+5mu2)+(5mu3+5mu4)+(5mu5+5mu6)+(5mu7+5mu8)
giải các phương trình
a) (3x-2)(3x-1) = (3x+1)2
b) (4x-1)(x+1) = (2x-3)2
c) (5x+1)2 = (7x-3)(7x+2)
d) (4-3x)(4+3x)=(9x-3)(1-x)
e) x(x+1)(x+2)(x+3)=24
g) (7x - 2)2= (7x-3)(7x+2)
a) \(\left(3x-2\right)\left(3x-1\right)=\left(3x+1\right)^2\)
<=> \(9x^2-9x+2=9x^2+6x+1\)
<=> \(15x=1\) <=> \(x=\frac{1}{15}\)
b) \(\left(4x-1\right)\left(x+1\right)=\left(2x-3\right)^2\)
<=> \(4x^2+3x-1=4x^2-12x+9\)
<=> \(15x^2=10\) <=> \(x=\frac{2}{3}\)
c) \(\left(5x+1\right)^2=\left(7x-3\right)\left(7x+2\right)\) <=> \(25x^2+10x+1=49x^2-7x-6\)
<=> \(24x^2-17x-7=0\) <=> \(24x^2-24x+7x-7=0\)
<=> \(\left(24x+7\right)\left(x-1\right)=0\) <=> \(\orbr{\begin{cases}x=-\frac{7}{24}\\x=1\end{cases}}\)
d) (4 - 3x)(4 + 3x) = (9x - 3)(1 - x)
<=> 16 - 9x2 = 12x - 9x2 - 3
<=> 12x = 19
<=> x = 19/12
e) x(x + 1)(x + 2)(x + 3) = 24
<=> (x2 + 3x)(x2 + 3x + 2) = 24
<=> (x2 + 3x)2 + 2(x2 + 3x) - 24 = 0
<=> (x2 + 3x)2 + 6(x2 + 3x) - 4(x2 + 3x) - 24 = 0
<=> (x2 + 3x + 6)(x2 + 3x - 4) = 0
<=> \(\orbr{\begin{cases}x^2+3x+6=0\\x^2+3x-4=0\end{cases}}\)
<=> \(\orbr{\begin{cases}\left(x+\frac{3}{2}\right)^2+\frac{15}{4}=0\left(vn\right)\\\left(x+4\right)\left(x-1\right)=0\end{cases}}\)
<=> \(\orbr{\begin{cases}x=-4\\x=1\end{cases}}\)
g) (7x - 2)2 = (7x - 3)(7x + 2)
<=> 49x2 - 28x + 4 = 49x2 - 7x - 6
<=> 21x = 10 <=> x = 10/21
giải các phương trình
a) (3x-2)(3x-1) = (3x+1)2
b) (4x-1)(x+1) = (2x-3)2
c) (5x+1)2 = (7x-3)(7x+2)
d) (4-3x)(4+3x)=(9x-3)(1-x)
e) x(x+1)(x+2)(x+3)=24
g) (7x - 2)2= (7x-3)(7x+2)
tìm x : (7x+3)2-(7x-1)(7x-3)=-12
\(\left(7x+3\right)^2-\left(7x-1\right)\left(7x-3\right)=-12\)
\(\Rightarrow49x^2+42x+9-\left(49x^2-21x-7x+3\right)=-12\)
\(\Rightarrow70x+18=0\) \(\Rightarrow x=-\dfrac{18}{70}=-\dfrac{9}{35}\)