tìm X:
A, X + 5 + 1458 = 1533
B, X+ 4210+ 213 = 17689
C, X x 9 - 109 = 13974
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5 x X + 6 x X - X = 4210
X x ( 5 + 6 - 1 ) = 4210
X x 10 = 4210
X = 4210 : 10
X = 421
\(5.x+6.x-x=4210\)
\(x.\left(5+6-1\right)=4210\)
\(x.10=4210\)
\(x=4210:10\)
\(x=421\)
`@` `\text {Ans}`
`\downarrow`
`a)`
\(2^{n+3}\cdot5^{n+3}=20^9\div2^9\)
`=>`\(\left(2\cdot5\right)^{n+3}=\left(20\div2\right)^9\)
`=>`\(10^{n+3}=10^9\)
`=>`\(n+3=9\)
`=> n = 9 - 3`
`=> n= 6`
Vậy, `n=6`
`b)`
\(3^{n+5}-3^{n+4}=1458\)
`=> 3^n*3^5 - 3^n*3^4 = 1458`
`=> 3^n*(3^5 - 3^4) = 1458`
`=> 3^n*162 = 1458`
`=> 3^n = 1458 \div 162`
`=> 3^n = 9`
`=> 3^n = 3^2`
`=> n=2`
Vậy, `n=2.`
`c)`
\(5^{n+3}+5^{n+2}=3750\)
`=> 5^n*5^3 + 5^n*5^2 = 3750`
`=> 5^n*(5^3+5^2) = 3750`
`=> 5^n*150 = 3750`
`=> 5^n = 3750 \div 150`
`=> 5^n =25`
`=> 5^n = 5^2`
`=> n=2`
Vậy, `n=2.`
`d)`
\(\dfrac{2}{7}x+\dfrac{3}{14}x=\dfrac{1}{2}\)
`=> 1/2x = 1/2`
`=> x = 1/2 \div 1/2`
`=> x=1`
Vậy, `x=1`
`e)`
\(\dfrac{x+2}{-3}=\dfrac{-2}{x+3}\)
`=> (x+2)(x+3) = -3*(-2)`
`=> (x+2)(x+3) = -6`
`=> x(x+3) + 2(x+3) = -6`
`=> x^2 + 3x + 2x + 6 = -6`
`=> x^2 + 5x + 6 - 6 = 0`
`=> x^2 + 5x = 0`
`=> x(x+5) = 0`
`=>`\(\left[{}\begin{matrix}x=0\\x+5=0\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
Vậy, `x \in {0; -5}`
`@` `\text {Kaizuu lv u}`
\(a.\)
\(\Leftrightarrow x-5+x-7=-12.\)
\(\Leftrightarrow x=-12+-12\)
\(\Leftrightarrow x=-24\)
\(b.\)
\(\Leftrightarrow3x+2x=-109+44\)
\(\Leftrightarrow5x=-65\)
\(\Rightarrow x=-13\)
\(c.\)
\(\Leftrightarrow2x-10-15+5x=-109\)
\(\Leftrightarrow2x-5x=-109+15+10\)
\(\Leftrightarrow3x=-84\)
\(\Rightarrow x=-28\)
\(d.\)
Mik ko biết làm dạng này!Xin lỗi bạn nhé!
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3x.213=1458
=>3x=1458:213
=>3x=486/71
=> x không tồn tại
minh cung co cau hoi giong ban ne nhung van chua co cau tra loi
mn oi giup minh voi con 2 phut nua la minh phai nop bai rui huhuhu help me
a) 120 - 20 : x = 110
20:x= 120 - 110
20:x= 10
x= 20:10=2
b) 213 - ( x - 13 ) = 1442 : 14
213 - (x-13)=103
x-13= 213 - 103
x-13=110
x=110+13
x=123
c) 2550 : [ 120 - ( x - 5 ) ] = 25
120 - (x-5) = 2550:25
120 - (x-5)=102
x-5 = 120 - 102
x-5= 18
x=18+5
x=23
a, X + 5 + 1458 = 1533
X + 1463 = 1533
X = 1533 - 1463
X = 70
b, X + 4210 + 213 = 17689
X + 4423 = 17689
X = 17689 - 4423
X = 13266
c, X x 9 - 109 = 13974
X x 9 = 13974 + 109
X x 9 = 14083
X = 14083: 9
X = 14083/9