Tìm X biết:
a,x^2-8x=0
b,x^2-2020x+2019=0
c,(2x-1)^2-(x+5)^2=0
Bài 1
a)Tìm a,b,c biết a^2-2a+b^2+4b+4c^2-4c+6=0
Bài 2:Tìm x,biết
2(x^2+8x+16)-x^2+4=0
Mọi người làm ơn giúp mình với.Ai nhanh mình tick.Cảm ơn mọi người rất nhiều
\(2\left(x^2+8x+16\right)-x^2+4=0\)
\(\Leftrightarrow2x^2+16x+32-x^2+4=0\)
\(\Leftrightarrow x^2+16x+36=0\)
\(\Leftrightarrow x^2+16x+64=28\)
\(\Leftrightarrow\left(x+8\right)^2=28\)
\(\Leftrightarrow\orbr{\begin{cases}x_1=\sqrt{28}-8\\x_2=-\sqrt{28}-8\end{cases}}\)
\(2\left(x^2+8x+16\right)-x^2+4=0\)
\(2x^2+16x+32-x^2+4=0\)
\(x^2+16x+36=0\)
\(x^2+16x+64=28\)
\(\left(x+8\right)^2=28\)
bình phương thì chia lm 2 trường hợp
lm tiếp phần sau
TÌm x biết :
a) (x-5)2=x-5
b) |x-1|+x=1
c) x2+4x-5=0
d) x2011+8x2008=0
e) x2-x-30=0
HELP ME !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
a) ta có : (x-5)\(^2\) =x-5
\(\Rightarrow\)(x-5)\(^2\) - (x-5)=0
\(\Rightarrow\)(x-5)(x-6)=0
\(\Rightarrow\)\(\orbr{\begin{cases}x-5=0\\x-6=0\end{cases}}\)
\(\Rightarrow\)\(\orbr{\begin{cases}x=5\\x=6\end{cases}}\)
a)\(\left(x-5\right)^2=x-5\Leftrightarrow\left(x-5\right)^2-\left(x-5\right)=0\Leftrightarrow\left(x-5\right)\left(x-6\right)=0\Leftrightarrow\orbr{\begin{cases}x=5\\x=6\end{cases}}\)
b)\(\left|x-1\right|+x=1\)
TH1 Với \(x\ge1\Rightarrow x-1+x=1\Leftrightarrow x=1\left(tm\right)\)
TH2: Với \(x< 1\Rightarrow1-x+x=1\Leftrightarrow1=1\)luôn đúng. suy ra phương trình có nghiệm với mọi x<1.
Vậy phương trình đã cho có các nghiệm là \(x\le1.\)
Tìm x biết:
a) (3x³ + x² – 13x + 5) : (x² + 2x – 1) = 10
b) (x⁴ – 2x² – 8) : (x – 2) = 0
c) \(\dfrac{x^2-4x}{x^2-8x+16}\)= 0
b: \(\Leftrightarrow x^4-4x^2+2x^2-8=0\)
\(\Leftrightarrow x+2=0\)
hay x=-2
Tìm x biết : \(2019x^2-2020x+1\text{=}0\)
2019x^2 - 2020x + 1 = 0
=> 2019x^2 - 2019x - x + 1 = 0
=> 2019x(x - 1) - (x - 1) = 0
=> (2019x - 1)(x - 1) = 0
=> 2019x - 1 =0 hoặc x - 1 = 0
=> 2019x = 1 hoặc x = 1
=> x = 1/2019 hoặc x = 1
Tìm x, biết:
a, 1/4 + 1/3 : 2x = -5
b, ( 3x - 1/4 ) . ( x + 1/2 ) = 0
c, ( 2x - 5 ) . ( 3/2x + 9 ) . ( 0,3x - 12 ) = 0
a)\(\frac{1}{4}+\frac{1}{3}:2x=-5\)
\(\frac{1}{3}:2x=-5-\frac{1}{4}\)
\(\frac{1}{3}:2x=-\frac{21}{3}\)
\(2x=\frac{1}{3}:\left(\frac{-21}{3}\right)\)
\(2x=-\frac{1}{21}\)
\(x=\frac{-1}{42}\)
b)\(\left(3x-\frac{1}{4}\right).\left(x+\frac{1}{2}\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}3x-\frac{1}{4}=0\\x+\frac{1}{2}=0\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}3x=\frac{1}{4}\\x=-\frac{1}{2}\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{1}{12}\\x=-\frac{1}{2}\end{array}\right.\)
c)\(\left(2x-5\right).\left(\frac{3}{2}x+9\right).\left(0,3x-12\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}2x-5=0\\\frac{3}{2}x+9=0\\0,3x-12=0\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}2x=5\\\frac{3}{2}x=-9\\0,3x=12\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=-6\\x=40\end{array}\right.\)
a) 1/4 + 1/3 : 2x = -5
=> 1/3 : 2x = -5 - 1/4
=> 1/3 : 2x = -21/4
=> 2x = 1/3 : (-21/4) = -4/63
=> x = -4/63 : 2 = -2/63
tìm x , y thuộc Z biết :
a, 4.(x +1 ) - (3x-1) = 14
b, (x^2 - 9 ). (x +2 )=0
c,(x^2 + 9 ) . (2x - 4) = 0
d, xy + 2x - y = 2
tìm x , y thuộc Z biết ;
a, 4 .( x+1) - (3x - 1) = 14
b, (x^2 - 9 ). (x+ 2) =0
c, (x^2 +9) . (2x -4) =0
d, xy +2x -y =2
a)4x+4-3x+1=14
x+5=14
x=11
b)trường hợp 1 x2-9=0
x2=9
->x=3;-3
-trường hợp 2: x+2=0
x=-2
c)-th1:x2+9=0
x2=-9
->x rỗng
d)xy+2x-y-2=0
(xy-y)+(2x-2)=0
y(x-1)+2(x-1)=0
(y+2)(x-1)=0
th1: y+2=0
y=-2
th2:x-1=0
x=1
(th1: trường hợp 1)
Tìm x thuộc Q, biết rằng:
a, 11/12 - ( 2/5 + x ) = 2/3
b, 2x . ( x - 1/7 ) = 0
c, 3/4 + 1/4 : x = 2/5
a, 11/12 - ( 2/5 + x ) = 2/3
<=> \(\frac{2}{5}+x=\frac{11}{12}-\frac{2}{3}=\frac{1}{4}\)
=> x=\(\frac{1}{4}-\frac{11}{12}=-\frac{2}{3}\)
b, 2x . ( x - 1/7 ) = 0
<=>\(\left[\begin{array}{nghiempt}x=0\\x-\frac{1}{7}=0\end{array}\right.\)<=> \(\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{7}\end{array}\right.\)
vậy x={\(0;\frac{1}{7}\)}
c, 3/4 + 1/4 : x = 2/5
<=>\(\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}=-\frac{7}{20}\)
<=> \(x=\frac{1}{4}:\left(-\frac{7}{20}\right)=-\frac{5}{7}\)
vậy x=-5/7
a) \(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)
\(\Leftrightarrow\frac{11}{12}-\frac{2}{5}-x=\frac{2}{3}\)
\(\Leftrightarrow-x=\frac{2}{3}-\frac{11}{12}+\frac{2}{5}=\frac{3}{20}\)
\(\Leftrightarrow x=-\frac{3}{20}\)
b) \(2x\left(x-\frac{1}{7}\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x-\frac{1}{7}=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{7}\end{array}\right.\)
c) \(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
\(\Leftrightarrow\frac{1}{4x}=\frac{2}{5}-\frac{3}{4}=-\frac{7}{20}\)
\(\Leftrightarrow4x=\frac{-20}{7}\)
\(\Leftrightarrow x=-\frac{5}{7}\)
a) \(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)
\(\frac{2}{5}+x=\frac{11}{12}-\frac{2}{3}\)
\(\frac{2}{5}+x=\frac{1}{4}\)
\(x=\frac{1}{4}-\frac{2}{5}\)
\(x=-\frac{3}{20}\)
Vậy \(x=-\frac{3}{20}\)
b) \(2x\left(x-\frac{1}{7}\right)=0\)
\(\Rightarrow\begin{cases}2x=0\\x-\frac{1}{7}=0\end{cases}\Rightarrow\begin{cases}x=0\\x=\frac{1}{7}\end{cases}\)
Vậy x = 0 hoặc \(x=\frac{1}{7}\)
c) \(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\)
\(\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\)
\(\frac{1}{4}:x=-\frac{7}{20}\)
\(x=\frac{1}{4}:\left(-\frac{7}{20}\right)\)
\(x=-\frac{5}{7}\)
Vậy \(x=-\frac{5}{7}\)
Tìm x, biết:
a) ( 6x3+x2) : 2x - 3x (x-1)+2=0
b) (5x4-3x2) : x2-x(5x+6)=0
Lời giải:
a.
PT $\Leftrightarrow 3x^2+\frac{x}{2}-3x^2+3x+2=0$
$\Leftrightarrow \frac{7}{2}x+2=0$
$\Leftrightarrow \frac{7}{2}x=-2$
$\Leftrightarrow x=-2: \frac{7}{2}=\frac{-4}{7}$
b.
PT $\Leftrightarrow 5x^2-3-5x^2-6x=0$
$\Leftrightarrow -3-6x=0$
$\Leftrightarrow 6x=-3$
$\Leftrightarrow x=\frac{-3}{6}=\frac{-1}{2}$