7.3x-1 -3x+2=-540
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Giải bất phương trình
7
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Đọc tiếp
Giải bất phương trình 7 . 3 x + 1 + 5 x + 3 ≤ 3 x + 4 + 5 x + 2
A. x ≤ -1
B. x ≥ -1
C. x ≤ 0
D. x ≥ 0
2/3.3x+1 - 7.3x = -405
\(\dfrac{2}{3}\cdot3^{x+1}-7\cdot3^x=-405\)
\(\Rightarrow3^x\cdot\left(\dfrac{2}{3}\cdot3-7\right)=-405\)
\(\Rightarrow3^x\cdot\left(2-7\right)=-405\)
\(\Rightarrow3^x\cdot-5=-405\)
\(\Rightarrow3^x=-405:-5\)
\(\Rightarrow3^x=81\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
Vậy: \(x=4\)
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\(\Leftrightarrow3\cdot\dfrac{2}{3}\cdot3^x-7\cdot3^x=-405\)
=>\(-5\cdot3^x=-405\)
=>3^x=81
=>x=4
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Phân tích đa thức sau thành nhân tử bằng phương pháp dùng bằng đẳng thức
1.x^2-7x+10
2.x^2+3x+2
3.x^2-7x+12
4.x^2+7x+12
5.16x-5x^2-3
6.6x^2+7x-3
7.3x^2-3x-6
8.3x^2+3x-6
9.6x^2-13x+6
10 6x^2+15x+6
11.6x^2-20x+6
12.8x^2+5x-3
1) x2 -7x + 10 = x2 - 2x - 5x + 10 = x(x - 2) - 5(x - 2) = (x - 5)(x - 2)
2) x2 + 3x + 2 = x2 + 2x + x + 2 = x(x + 2) + (x + 2) = (x + 1)(x + 2)
3) x2 - 7x + 12 = x2 - 3x - 4x + 12 = x(x - 3) - 4(x - 3) = (x - 3)(x - 4)
4) x2 + 7x + 12 = x2 + 3x + 4x + 12 = x(x + 3) + 4(x + 3) = (x + 3)(x + 4)
5) 16x - 5x2 - 3 = 15x - 5x2 + x - 3 = -5x(x - 3) + (x - 3) = (x - 3)(1 - 5x)
6) 6x2 + 7x - 3 = 6x2 - 2x + 9x - 3 = 2x(3x - 1) + 3(3x - 1) = (2x + 3)(3x - 1)
7) 3x2 - 3x - 6 = 3x2 - 6x + 3x - 6 = 3x(x - 2) + 3(x - 2) = (x - 2)(3x + 3) = 3(x - 2)(x + 1)
8) 3x2 + 3x - 6 = 3x2 - 3x + 6x - 6 = 3x(x - 1) + 6(x - 1) = (x - 1)(3x + 6) = 3(x - 1)(x + 2)
9) 6x2 - 13x + 6 = 6x2 - 9x - 4x + 6 = 3x(2x - 3) - 2(2x - 3) = (3x - 2)(2x - 3)
10) 6x2 + 15x + 6 = 6x2 + 12x + 3x + 6 = 6x(x + 2) + 3(x + 2) = (x + 2)(6x + 3) = 3(x + 2)(3x + 1)
11) 6x2 - 20x + 6 = 6x2 - 18x - 2x + 6 = 6x(x -3) - 2(x - 3) = (6x - 2)(x - 3) = 2(3x - 1)(x - 3)
12) 8x2 + 5x - 3 = 8x2 + 8x - 3x - 3 = 8x(x + 1) - 3(x + 1) = (x + 1)(8x - 3)
1 Tìm x
a) (3/4-1/5-1/6)::1/30-|3x-3|=2
b)5/7.3x-8/5=35/9
c)13/15-(13/21+x).7?12=7/10
d)(+1/4-1/3):(2+1/6-1/4)==7/46
a) 210 : x - \(\dfrac{1}{2}\) = 20,5
b) 7.3x + 20.3x = 325
`@` `\text {Ans}`
`\downarrow`
`a)`
`210 \div x - 1/2 = 20,5`
`=> 210 \div x = 20,5 + 1/2`
`=> 210 \div x =21`
`=> x = 210 \div 21`
`=> x = 10`
Vậy, `x = 10.`
`b)`
`7 * 3^x + 20*3^x = 3^25`
`=> 3^x * (7+20) = 3^25`
`=> 3^x * 27 = 3^25`
`=> 3^x * 3^3 = 3^25`
`=> 3^x = 3^25 \div 3^3`
`=> 3^x = 3^22`
`=> x = 22`
Vậy, `x = 22.`
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a) \(210:x-\dfrac{1}{2}=20,5\)
\(\Rightarrow210:x=20,5+\dfrac{1}{2}\)
\(\Rightarrow210:x=21\)
\(\Rightarrow x=\dfrac{210}{21}\)
\(\Rightarrow x=10\)
b) \(7\cdot3^x+20\cdot3^x=3^{25}\)
\(\Rightarrow3^x\cdot\left(7+20\right)=3^{25}\)
\(\Rightarrow3^x\cdot27=3^{25}\)
\(\Rightarrow3^x\cdot3^3=3^{25}\)
\(\Rightarrow3^{x+3}=3^{25}\)
\(\Rightarrow x+3=25\)
\(\Rightarrow x=25-3\)
\(\Rightarrow x=22\)
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\(a)\)
\(210:x-\dfrac{1}{2}=20,5\)
\(210:x=20,5+\dfrac{1}{2}\)
\(210:x=21\)
\(x=210:21\)
\(x=10\)
Vậy \(x=10\)
\(b)\)
\(7.3^x+20.3^x=3^{25}\)
\(3^x.\left(7+20\right)=3^{25}\)
\(3^x.27=3^{25}\)
\(3^x.3^3=3^{25}\)
\(3^x=3^{25}:3^3\)
\(3^x=3^{22}\)
\(x=22\)
Vậy \(x=22\)
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A)7.x-1-3x+2=-540
B)(x-1)4=x-1
â, 7x - 1 - 3x + 2 = -540
=> 4x + 1 = -540
=> 4x = -541
=> x = -541/4
b, (x - 1)4 = x - 1
=> 4x - 4 - x + 1 = 0
=> 3x - 3 = 0
=> 3(x - 1) = 0
=> x - 1 = 0
=> x = 1
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7.3x+20.3x=325
7 . 3x + 20 . 3x = 325
=> 3x ( 7+20) = 325
=> 3x . 27 = 325
=> 325-x = 27 = 33
=> 25 - x = 3
=> x = 25 - 3 = 22
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\(7.3^x+20.3^x=3^{25}\)
\(\Rightarrow3^x\left(7+20\right)=3^{25}\)
\(\Rightarrow3^x.27=3^{25}\)
\(\Rightarrow3^x.3^3=3^{25}\)
\(\Rightarrow3^{x+3}=3^{25}\Rightarrow x+3=25\Rightarrow x=22\)
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7.3x *(x+1)^2 -5x^3(x+1)+7(x+1)
8.(2x+1)^2-(x-1)^2
9.(x+5)^2-(x-7)^2
10.9 (x+5)^2-(x-7)^2
Tìm x
(-x).3/2+9/7/6.(7.3x+2)=95x
23 tháng 9 2021 lúc 22:13
x thoả mãn 7.3x = 189
x =
A 3 B 9 C 6
\(7.3^x=189\)
\(\Rightarrow3^x=27\)
\(\Rightarrow3^x=3^3\Rightarrow x=3\)
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