Tìm X biết (X+1) + ( X+3) + (X+5) +...+(X+19) = 150
Tìm x thuộc Z, biết:
1) \(3.5^{x+5}+4.5^{x-3}=19.5^{10}\)
2) \(6.8^{x-1}+8^{x+1}=6.8^{19}=8^{21}\)
3) \(5.2^x+3.2^{x+2}=5.2^5+3.2^7\)
tìm các số nguyên x,y biết \(\frac{x}{y}=\frac{-3}{11}\)
b/\(\frac{x}{y-1}=\frac{5}{-19}\)
tìm x biết
\(\frac{x-1}{2006}+\frac{x-10}{1997}+\frac{x-19}{1998}=3\)
Bạn sửa đề lại nha.
\(\frac{x-1}{2006}+\frac{x-10}{1997}+\frac{x-19}{1988}=3\)
=>\(\frac{x-1}{2006}+\frac{x-10}{1997}+\frac{x-19}{1988}-3=0\)
=>\(\left(\frac{x-1}{2006}-1\right)+\left(\frac{x-10}{1997}-1\right)+\left(\frac{x-19}{1988}-1\right)=0\)
=>\(\frac{x-1-2006}{2006}+\frac{x-10-1997}{1997}+\frac{x-19-1988}{1988}=0\)
=>\(\frac{x-2007}{2006}+\frac{x-2007}{1997}+\frac{x-2007}{1988}=0\)
=>\(\left(x-2007\right).\left(\frac{1}{2006}+\frac{1}{1997}+\frac{1}{1988}\right)=0\)
Vì \(\frac{1}{2006}+\frac{1}{1997}+\frac{1}{1988}\ne0\)
=>x-2007=0
=>x=2007
Tìm x \(\in Z\) biết
\(5-x-10-\left(-15\right)\)
\(10-\left(x\right)=7\)
\(\left(x-5\right)-7=19-21\)
\(2x+\left(x\right)=3x\)
\(19-x+\left(x-4\right)=0\Leftrightarrow\left(x-4\right)=x-19\)
\(\left|x-10\right|+10=x\)
\(\left|x-3\right|=x=3\)
\(\left|x\right|+\left|x+1\right|+\left|x+2\right|=24x\)
Tìm x biết (x+1)+(x+3)+(x+5)+....+(x+19)=350
(x+1)+(x+3)+(x+5)+....+(x+19)=350
x =350-(1+3+5+.................+19)
x =350-100
x =250:10
x =25
Tìm x, biết : a) (x + 1) + (x + 3) + (x + 5) + (x + 7) + … + (x + 19) = 200
Tìm x \(\in\) Z :
1) -12(x - 5) + 7(3 - x) = 5
2) (x - 2) . (x + 4) = 0
3) (7 - x) . (x + 19) = 0
4) (x - 2) . (x + 15) = 0
999 - 888 - 111 + 111 - 111 + 111 - 111
= 111 - 111 + 111 - 111 + 111 - 111
= 0 + 111 - 111 + 111 - 111
= 111 - 111 + 111 - 111
= 0 + 111 - 111
= 111 - 111
= 0
999 - 888 - 111 + 111 - 111 + 111 - 111
= 111 - 111 + 111 - 111 + 111 - 111
= 0 + 111 - 111 + 111 - 111
= 111 - 111 + 111 - 111
= 0 + 111 - 111
= 111 - 111
= 0
1) -12(x-5)+7(3-x)=5
=> (-12x)-(-60)+21-7x=5
=> (-12x)+60+21-7x =5
=> (-12x)+81-7x =5
=> (-12x)-7x =5-81
=> x.[(-12)-7)] =-76
=> x.(-19) =-76
=> x =(-76):(-19)
=> x =4
Vậy x=4
2) (x-2).(x+4)=0
Để tích trên bằng 0 <=> x-2=0=>x=0+2=>x=2 và x+4=0=>x=0-4=>x=-4
Vậy x =-4;2
3) (7-x).(x+19)=0
Để tích trên bằng 0 <=> 7-x=0=>x=7-0=>x=7 và x+19=0=>x=0-19=>x=-19
Vậy x=-19;7
4) (x-2).(x+15)=0
Để tích trên bằng 0 <=> x-2=0=>x=0=2=>x=2 và x+15=0=>x=0-15=>x=-15
Vậy x=-15;2
Tìm \(x\) biết: \(\left(\frac{1}{3\cdot5}+\frac{1}{5\cdot7}+\frac{1}{7\cdot9}+...+\frac{1}{19\cdot21}\right)\cdot x=\frac{9}{7}\)
Bước 1: \(\left(\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+...+\frac{1}{19\times21}\right)=\frac{1}{7}\)
Bước 2: \(x=\frac{9}{7}\div\frac{1}{7}=9\)
tìm (x;y) thuộc Z,biết:
\(\frac{x}{y-1}\)=\(\frac{5}{-19}\)
=> x.(-19)= 5.(y-1)
=> x.(-19)=5.y-5
=> x.(-19)=5.(y-1)
=> x=5; y-1=(-19)
=> y=(-19)+1=-18
Vậy y=-18;x=5
=> x.(-19)= 5.(y-1)
=> x.(-19)=5.y-5
=> x.(-19)=5.(y-1)
=> x=5; y-1=(-19)
=> y=(-19)+1=-18
Vậy y=-18;x=5