Tìm x
a) | 3x - 1 | = x + 2
b. | x + 1 | + |x + 2 | + |x + 3 | +....... + | x + 100 | = 102 x
Bài 1
a) Thực hiện phép tính: (3x-1)(2x+7)-(12x^3+8x^2-14x) : 2
b) Tính nhanh: B=(63^3-37^3) : 26+63.37
Bài 2: phân tích đa thức thành nhân tử
a) xy^2-25x
b) x(x-y)+2x-2y
c) x^3-3x^2-4x+12
Bài 3:tìm x
a) (x+2)^2+(x-1)^2+(x-3)(x+3)=-8
b) 2021x(x-2020)-x+2020=8
Các bn giúp mk với mk tk cho ai nhanh nhất nè !!!
pls help me mk đang cần vội :(
Bài 1:
\(a,=6x^2+19x-7-6x^3-4x^2+7x=-6x^3+2x^2+26x-7\\ b,B=26\cdot\left(63^2+63\cdot37+37^2\right):26+63\cdot37\\ =63^2+63\cdot37+37^2+63\cdot37\\ =\left(63+37\right)^2=100^2=10000\)
Bài 2:
\(a,=x\left(y^2-25\right)=x\left(y-5\right)\left(y+5\right)\\ b,=\left(x-y\right)\left(x+2\right)\\ c,=\left(x-3\right)\left(x^2-4\right)=\left(x-2\right)\left(x-3\right)\left(x+2\right)\)
Bài 2:
b: \(=\left(x-y\right)\left(x+2\right)\)
Tìm x
a) -3 1/2 : (4/5-1/2x) = 2^2
b) 2x + 3x = 5
c) -2/3x - 1/3x = -2
d) -2/3 (x+1) - 1/2 = -1/3
a: =>-7/2:(4/5-1/2x)=4
=>4/5-1/2x=-7/2:4=-7/8
=>1/2x=4/5+7/8=67/40
=>x=67/20
b: =>5x=5
=>x=1
c: =>x(-2/3-1/3)=-2
=>-x=-2
=>x=2
d: =>-2/3(x+1)=-1/3+1/2=1/6
=>x+1=-1/6:2/3=-1/6*3/2=-3/12=-1/4
=>x=-1/4-1=-5/4
1. Rút gọn
a, A=(4x+3y)2 + (4x-3y)2
b,B=(x-23)-(x+2)3
c,C=(x+2y)2+2.(x+2y) (x-2y) + (x-2y)2
2. Tìm x
a, x2+12x+36=0
b,16x2-8x+1=0
c,x3+3x2+3x+1=0
2a) pt <=> (x + 6)^2 = 0
<=> x = -6
b) pt <=> (4x - 1)^2 = 0
<=> x = 1/4
c) pt<=> (x + 1)^3 = 0
<=> x = -1
Bài 1:
a: Ta có: \(A=\left(4x+3y\right)^2+\left(4x-3y\right)^2\)
\(=16x^2+24xy+9y^2+16x^2-24xy+9y^2\)
\(=32x^2+18y^2\)
b: Ta có: \(B=\left(x-2\right)^3-\left(x+2\right)^3\)
\(=x^3-6x^2+12x-8-x^3-6x^2-12x-8\)
\(=-12x^2-24\)
1. Rút gọn
a, A=(4x+3y)2 + (4x-3y)2
b,B=(x-23)-(x+2)3
c,C=(x+2y)2+2.(x+2y) (x-2y) + (x-2y)2
2. Tìm x
a, x2+12x+36=0
b,16x2-8x+1=0
c,x3+3x2+3x+1=0
Bài 2:
a: Ta có: \(x^2+12x+36=0\)
\(\Leftrightarrow x+6=0\)
hay x=-6
b: Ta có: \(16x^2-8x+1=0\)
\(\Leftrightarrow4x-1=0\)
hay \(x=\dfrac{1}{4}\)
Bài 1:
a: Ta có: \(A=\left(4x+3y\right)^2+\left(4x-3y\right)^2\)
\(=16x^2+24xy+9y^2+16x^2-24xy+9y^2\)
\(=32x^2+18y^2\)
b: Ta có: \(B=\left(x-2\right)^3-\left(x+2\right)^3\)
\(=x^3-6x^2+12x-8-x^3-6x^2-12x-8\)
\(=-12x^2-24\)
c: Ta có: \(C=\left(x+2y\right)^2+2\left(x+2y\right)\left(x-2y\right)+\left(x-2y\right)^2\)
\(=\left(x+2y+x-2y\right)^2\)
\(=4x^2\)
Tìm x :
a) (x + 2) - x(x + 3) = 2
b) (x + 2)(x -2) - (x + 1)2 = 7
c) 6x2 - (2x + 1)(3x - 2) = 1
d) (x + 2)(x + 3) - (x - 2)(x + 1) = 2
e) 6(x - 1)( x + 1) - (2x - 1)(3x + 2) + 3 = 0
a (x + 2) - x(x + 3) = 2
x + 2 - x(x + 3) - 2 = 0
x + x(x + 3) = 0
x(1 + x + 3) = 0
x(x + 4) = 0
x = 0 hoặc x + 4 = 0
*) x + 4 = 0
x = -4
Vậy x = -4; x = 0
b) (x + 2)(x - 2) - (x + 1)² = 7
x² - 4 - x² - 2x - 1 = 7
-2x - 5 = 7
-2x = 7 + 5
-2x = 12
x = 12 : (-2)
x = -6
c) 6x² - (2x + 1)(3x - 2) = 1
6x² - 6x² + 4x - 3x + 2 = 1
x + 2 = 1
x = 1 - 2
x = -1
d) (x + 2)(x + 3) - (x - 2)(x + 1) = 2
x² + 3x + 2x + 6 - x² - x + 2x + 2 = 2
6x + 8 = 2
6x = 2 - 8
6x = -6
x = -6 : 6
x = -1
e) 6(x - 1)(x + 1) - (2x - 1)(3x + 2) + 3 = 0
6x² - 6 - 6x² - 4x + 3x + 2 + 3 = 0
-x - 1 = 0
x = -1
Tìm x:
a) (2x - 1) (x^2 - x + 1) = 2x^3 - 3x^2 + 2
b) (x + 1) (x^2 + 2x + 4) - x^3 - 3x^2 + 16 = 0
c) (x + 1) (x + 2) (x + 5) - x^3 - 8x^2 = 27
a) Ta có: \(\left(2x-1\right)\left(x^2-x+1\right)=2x^3-3x^2+2\)
\(\Leftrightarrow2x^3-2x^2+2x-x^2+x-1-2x^3+3x^2-2=0\)
\(\Leftrightarrow3x=3\)
hay x=1
Vậy: S={1}
b) Ta có: \(\left(x+1\right)\left(x^2+2x+4\right)-x^3-3x^2+16=0\)
\(\Leftrightarrow x^3+2x^2+4x+x^2+2x+4-x^3-3x^2+16=0\)
\(\Leftrightarrow6x=-20\)
hay \(x=-\dfrac{10}{3}\)
c) Ta có: \(\left(x+1\right)\cdot\left(x+2\right)\left(x+5\right)-x^3-8x^2=27\)
\(\Leftrightarrow\left(x^2+3x+2\right)\left(x+5\right)-x^3-8x^2-27=0\)
\(\Leftrightarrow x^3+5x^2+3x^2+15x+2x+10-x^3-8x^2-27=0\)
\(\Leftrightarrow17x=17\)
hay x=1
tìm x
a /x/=+0,573=2
b/x+1 phần 3 / -4=-2
b: \(\left|x+\dfrac{1}{3}\right|-4=-2\)
\(\Leftrightarrow\left|x+\dfrac{1}{3}\right|=2\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=2\\x+\dfrac{1}{3}=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{3}\\x=-\dfrac{7}{3}\end{matrix}\right.\)
Tìm x
a) x + 2/5 = 1/2
b) x + 3/7 = 2/5 + 3/10
c) 19 - x = 8/5 - 3/4
\(a,x=\dfrac{1}{2}-\dfrac{2}{5}\)
\(x=\dfrac{1}{10}\)
\(b,x+\dfrac{3}{7}=\dfrac{7}{10}\)
\(x=\dfrac{7}{10}-\dfrac{3}{7}\)
\(x=\dfrac{19}{70}\)
\(c,19-x=\dfrac{17}{20}\)
\(x=19-\dfrac{17}{20}\)
\(x=\dfrac{363}{20}\)
Tìm X:
a, |5/3 -x| -|-5/6|=|-5/9|
b,|x+1/102|+|x+2/102|+...+|x+100/102| = 102x
a) |5/3 - x| - |-5/6| = |-5/9|
=> |5/3 - x| - 5/6 = 5/9
=> |5/3 - x| = 5/9 + 5/6
=> |5/3 - x| = 25/18
=> \(\orbr{\begin{cases}\frac{5}{3}-x=\frac{25}{18}\\\frac{5}{3}-x=-\frac{25}{18}\end{cases}}\)
=> \(\orbr{\begin{cases}x=\frac{5}{18}\\x=\frac{55}{18}\end{cases}}\)
a, \(\left|\frac{5}{3}-x\right|-\left|-\frac{5}{6}\right|=\left|-\frac{5}{9}\right|\)
\(\Leftrightarrow\left|\frac{5}{3}-x\right|-\frac{5}{6}=\frac{5}{9}\Rightarrow\left|\frac{5}{3}-x\right|=\frac{5}{9}+\frac{5}{6}=\frac{25}{18}\)
\(\Rightarrow\orbr{\begin{cases}\frac{5}{3}-x=\frac{25}{18}\\\frac{5}{3}-x=-\frac{25}{18}\end{cases}\Rightarrow}x.\)
b, \(\left|x+\frac{1}{102}\right|+\left|x+\frac{2}{102}\right|+...+\left|x+\frac{100}{102}\right|\ge0\)
\(\Rightarrow102x\ge0\Leftrightarrow x\ge0\)=> Ta có thể phá dấu GTTĐ
\(\Rightarrow x+\frac{1}{102}+x+\frac{2}{102}+...+x+\frac{100}{102}=102x\)
\(\Rightarrow100x+\frac{1+2+3+...+100}{102}=102x\Rightarrow2x\Rightarrow x.\)