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\(75\%\cdot x+\frac{3}{4}\cdot x+x=30\)
\(x\cdot\left(\frac{3}{4}+\frac{3}{4}+1\right)=30\)
\(x\cdot\frac{5}{2}=30\)
\(x=30\cdot\frac{2}{5}\)
\(x=12\)
a)1824 - { 526 + 2x } = 1420 - 318
1824 - { 526 + 2x } = 1102
526 + 2x = 1824 - 1102
526 + 2x = 722
2x = 722 - 526
2x = 196
x = 196 : 2
x = 98
b) [ 215 - { 3x - 18 } ] = 5225 : 25
[ 215 - { 3x - 18 } ] = 209
{ 3x - 18 } = 215 - 209
{ 3x - 18 } = 6
3x = 6 + 18
3x = 24
x = 24 : 3
x = 8
k cho minh nha
{1824 - ( 526 + 2x ) }+ 318 = 1420
{ 1824 - ( 526 + 2x ) } = 1420 - 318
{ 1824 - ( 526 + 2x ) } = 1102
526 + 2x = 1824 - 1102
526 + 2x = 722
2x = 722 - 526
2x = 196
x = 196 : 2
x = 98
\(x\left(x+1\right)-\left(x-2\right)=11\)
\(\Rightarrow x^2+x-x+2=11\)
\(\Rightarrow x^2+2=11\)
\(\Rightarrow x^2=11-2\)
\(\Rightarrow x^2=9\)
\(\Rightarrow x^2=3^2\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)
x+ \(\dfrac{30}{100}\)x=-1,3
x(1+\(\dfrac{30}{100}\))= -1,3
x. 1,3= -1,3
x = -1
Bài 1:
a: x/-2=-18/x
=>x2=36
=>x=6 hoặc x=-6
b: x/2+x/5=17/10
=>7/10x=17/10
hay x=17/7
1/2x3/2+1/3x4/2+1/4x5/2+1/5x6/2+.......+2/Xx(X+1)=2011/2013
2/2x3+2/3x4+2/4x5+2/5x6+.....+2/Xx(X+1)=2011/2013
2x(1/2x3+1/3x4+1/4x5+1/5x6+....+1/Xx(x+1)=2011/2013
1/2x3+1/3x4+1/4x5+1/5x6+....+1/Xx(X+1)=2011/4026
1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+.....+ 1/x-1/x+1=2011/4026
1/2-1/x+1=2011/4026
1/x+1=1/2-2011/4026
1/x+1=1/2013
Suy ra x=2012
\(\left(x+1\right).\left(x+1\right).\left(xx+1\right)=0\)
\(\left(x+1\right)^2.\left(xx+1\right)=0\)
\(\Rightarrow\left(x+1\right)^2=xx+1=0\)
TH1: \(\left(x+1\right)^2=0\) TH2: \(xx+1=0\)
\(x+1=0\) \(x^2+1=0\)
\(x=-1\) \(x^2=-1\)
\(\Rightarrow x\in\varnothing\)(vì ko có căn bậc 2 nào mang giá trị âm)
VẬY X=-1
CHÚC BN NĂM MỚI VUI VẺ !!!!!!!!
\(x^2+7⋮x+1\Leftrightarrow x\left(x+1\right)-\left(x-1\right)+6⋮x+1\)
\(\Rightarrow x+1\inƯ\left(6\right)=\left\{\pm1;\pm2;\pm3;\pm6\right\}\)
x + 1 | 1 | -1 | 2 | -2 | 3 | -3 | 6 | -6 |
x | 0 | -2 | 1 | -3 | 2 | -4 | 5 | -7 |