68-4x=2x+2^3 Tìm x
tìm x,y,z : 2x-3/5 = 3y+2/7 = z-1/3 và 4x - 6y +7z = 68
Ta có \(\dfrac{2x-3}{5}=\dfrac{3y+2}{7}=\dfrac{z-1}{3}=\dfrac{4x-6}{10}=\dfrac{6y+4}{14}=\dfrac{7z-7}{21}\)
Áp dụng t/c dtsbn:
\(\dfrac{4x-6}{10}=\dfrac{6y+4}{14}=\dfrac{7z-7}{21}=\dfrac{\left(4x-6y+7z\right)-6-4-7}{10-14+21}=\dfrac{68-17}{17}=3\\ \Rightarrow\left\{{}\begin{matrix}2x-3=15\\3y+2=21\\z-1=9\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=9\\y=\dfrac{19}{3}\\z=10\end{matrix}\right.\)
1) 2x. ( x - 5 ) + ( x - 2 ) . ( x + 3 )
2 ) ( 2 x - 5 ) . ( 1 - x ) - ( x - 3 ) . ( - 2x )
3 ) ( 4x - 3 ) . ( 4x - 3 ) - ( 3x + 2 ) . ( 3x - 2 )
4 ) ( 2x - 1 ) . ( 2x + 1 ) . ( 2x + 1 ) -4 . ( x2 + 1 )
5 ) 3x . ( 2x - 8 ) - ( 2 - 6x ) . ( 5 + x )
6 ) x . ( 3x - 18 ) - 3 . ( x - 4 ) . ( x - 2 ) + 8
7 ) ( x + 2 ) . ( x2 - 2x + 4 ) - x2 . ( x - 2 ) - 2x2
1) \(2x\left(x-5\right)+\left(x-2\right)\left(x+3\right)=2x^2-10x+x^2+3x-2x-6=3x^2-9x-6\)
2) \(\left(2x-5\right)\left(1-x\right)-\left(x-3\right)\left(-2x\right)=2x-2x^2-5+5x+2x^2-6x=x-5\)
3) \(\left(4x-3\right)\left(4x-3\right)-\left(3x+2\right)\left(3x-2\right)=\left(4x-3\right)^2-9x^2+4=16x^2-24x+9-9x^2+4\)
\(=7x^2-24x+13\)
4) \(\left(2x-1\right)\left(2x+1\right)\left(2x+1\right)-4\left(x^2+1\right)=\left(2x-1\right)[\left(2x+1\right)^2]-4x^2-4\)
\(=\left(2x-1\right)\left(4x^2+4x+4\right)-4x^2-4=8x^3+8x^2+8x-4x^2-4x-4-4x^2-4=8x^3+4x-8\)
5) \(3x\left(2x-8\right)-\left(2-6x\right)\left(5+x\right)=6x^2-24x-10-2x+30x+6x^2=12x^2+4x-10\)
6) \(x\left(3x-18\right)-3\left(x-4\right)\left(x-2\right)+8=3x^2-18x-3x^2+6x+12x-24+8=-16\)
7) \(\left(x+2\right)\left(x^2-2x+4\right)-x^2\left(x-2\right)-2x^2=x^3+8-x^3+2x^2-2x^2=8\)
tìm x: 68 - 4x = 2x + 219 : 216
tìm x biết:68-4x=2x+219:216
Tìm x:
68-4x=2x+219÷216
68-4x=2x+219/213
68-4x=2x+26
68=2x+26+4x
68=6x+26
68=6x+64
6x=68-64
6x=4
x=4/6
x=2/3
Phân tích đa thức thành nhân tử(tách hạng tử)
1)x^2+2x-3
2)x^2-5x+6
3)x^2+7x^2+12x
4)x^2-x-12
5)3x^2+3x-36
6)5x^2-5x-10
7)3x^2-7x-6
8)4x^2+4x-3
9)8x^2-2x-3
Phân tích đa thức thành nhân tử(tách hạng tử)
1)x^2+2x-3=x^2-x+3x-3=x(x-1)+3(x-1)=(x-1)(x+3)
2)x^2-5x+6=x^2-2x-3x+6=x(x-2)-3(x-2)=(x-2)(x-3)
3)x^2+7x+12=(x+3)(x+4)
4)x^2-x-12=(x-4)(x+3)
5)3x^2+3x-36=3[(x-3)(x+4)]
6)5x^2-5x-10=5[(x-2)(x+1) ]
7)3x^2-7x-6=(x-3)(3x+2)
8)4x^2+4x-3=4x^2+6x-2x-3=(2x-1)(2x+3)
9)8x^2-2x-3=8x^2+4x-6x-3=(4x-3)(2x+1)
1: \(x^2+2x-3=\left(x+3\right)\left(x-1\right)\)
2: \(x^2-5x+6=\left(x-2\right)\left(x-3\right)\)
3: \(x^2+7x^2+12x=4x\left(2x+3\right)\)
4: \(x^2-x-12=\left(x-4\right)\left(x+3\right)\)
5: \(3x^2+3x-36=3\left(x^2+x-12\right)=3\left(x+4\right)\left(x-3\right)\)
6: \(5x^2-5x-10=5\left(x^2-x-2\right)=5\left(x-2\right)\left(x+1\right)\)
Bài 2:Cho 5x=8y Tìm x,y biết a) x+y=26 b)x-y=30 c)3x+2y=68 d) 4x-3y=34
bài :3Cho 2x+1/3=4y+3/9 Tìm x,y biết 3x-5y=18
Thả like nà-.-
Tìm, x ,y z biết:
a) x,y,z tỉ lệ nghịch với 3,5,7 và 2x-y+3z=188
b) \( \frac{2x-3}{5}= \frac{3y+2}{7}=\frac{z-1}{3}\) và 4x-6y+7z=68
a, \(3x=5y=7z\Rightarrow\frac{x}{\frac{1}{3}}=\frac{y}{\frac{1}{5}}=\frac{z}{\frac{1}{7}}\)
\(\Rightarrow\frac{2x}{\frac{2}{3}}=\frac{y}{\frac{1}{5}}=\frac{3z}{\frac{3}{7}}\)
Áp dụng t/c
\(\Rightarrow\frac{2x}{\frac{2}{3}}=\frac{y}{\frac{1}{5}}=\frac{3z}{\frac{3}{7}}=\frac{2x-y+3z}{\frac{2}{3}-\frac{1}{5}+\frac{3}{7}}=\frac{188}{\frac{105}{94}}=210\)
\(\frac{x}{\frac{1}{3}}=210\Rightarrow x=70\)
\(\frac{y}{\frac{1}{5}}=210\Rightarrow y=42\)
\(\frac{z}{\frac{1}{7}}=210\Rightarrow z=30\)
thực hiện phép tính a) 5x-[2x+1-(2x-3)-(4x+1)]
b) (-3x^2+2x-1)+(4x^2-2x+3)
`Answer:`
a. \(5x-[2x+1-\left(2x-3\right)-\left(4x+1\right)]\)
\(=5x-\left(2x+1-2x+3-4x-1\right)\)
\(=5x-2x-1+2x-3+4x+1\)
\(=\left(5x-2x+2x+4x\right)+\left(-3-1+1\right)\)
\(=9x-3\)
b. \(\left(-3x^2+2x-1\right)+\left(4x^2-2x+3\right)\)
\(=-3x^2+2x-1+4x^2-2x+3\)
\(=\left(-3x^2+4x^2\right)+\left(2x-2x\right)+\left(-1+3\right)\)
\(=x^2+2\)