tìm y :
a 240 : y + 118 = 178
b \(\frac{2}{9}\)+ 1 = 1
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a)Ta có:5/3.x^2-1/2.x^2y
=(5/3-1/2).x^2y
= 7/6.x^2y(Bậc 3)
b)Ta có: 7/6.(-2)^2(-1)
= 7/6.4.(-1)
= 7/6.(-4)
=-28/6
a, - A=\(\dfrac{5}{3}\).x2.y-\(\dfrac{-1}{2}\).x2.y
=\(\dfrac{13}{6}\).x2.y
- Bậc= 3.
b, A=\(\dfrac{13}{6}\).(-2)2.(-1)
=\(\dfrac{13}{6}\).4.(-1)
=\(\dfrac{-26}{3}\)
\(1,Y=\left(1+3+3^2\right)+\left(3^3+3^4+3^5\right)+...+\left(3^{96}+3^{97}+3^{98}\right)\\ Y=\left(1+3+3^2\right)\left(1+3^3+...+3^{96}\right)\\ Y=13\left(1+3^3+...+3^{96}\right)⋮13\\ 2,A=\left(1+3\right)+\left(3^2+3^3\right)+...+\left(3^{2018}+3^{2019}\right)\\ A=\left(1+3\right)\left(1+3^2+...+3^{2019}\right)\\ A=4\left(1+3^2+...+3^{2019}\right)⋮4\\ 3,\Leftrightarrow2\left(x+4\right)=60\Leftrightarrow x+4=30\Leftrightarrow x=36\)
Hệ số góc bằng 2 `=> 3a+4 = 2 <=> a=-2/3`
Tung độ gốc bằng 1 `=> -b+3=1 <=> b=2`
`=> y=-2/3 x +2`
240 : y + 118 = 178
240 : y = 178 - 118
240 : y = 60
y = 240 : 60
y = 4
\(\left|x^2-1\right|=2x+1\left(dk:2x+1\ge0\Leftrightarrow2x\ge-1\Leftrightarrow x\le-\dfrac{1}{2}\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-1=2x+1\\x^2-1=-2x-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-1-2x-1=0\\x^2-1+2x+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x-2=0\\x^2+2x=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x-2+3=3\\x.\left(x+2\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x-1\right)^2=3\\\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x-1^2\right)-\left(\sqrt{3}\right)^2=0\\\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x-1-\sqrt{3}\right).\left(x-1+\sqrt{3}\right)=0\\\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x=1-\sqrt{3}\left(loai\right)\\x=1+\sqrt{3\left(loai\right)}\end{matrix}\right.\\\left[{}\begin{matrix}x=0\left(loai\right)\\x=-2\left(tm\right)\end{matrix}\right.\end{matrix}\right.\)
Vậy x = -2
9 T I C H sai buồn
\(A=\frac{\sqrt{x^3}}{\sqrt{xy}-2y}-\frac{2x}{x+\sqrt{x}-2\sqrt{xy}-2\sqrt{y}}.\frac{1-x}{1-\sqrt{x}}..\)
nhờ vào năng lực rinegan tối hậu của ta , ta có thể dễ dàng nhìn thấy mẫu chung
\(x+\sqrt{x}-2\sqrt{xy}-2\sqrt{y}=\sqrt{x}\left(\sqrt{x}-2\sqrt{xy}\right)+\left(\sqrt{x}-2\sqrt{y}\right)=\left(\sqrt{x}-2\sqrt{y}\right)\left(\sqrt{x}+1\right)\)
\(A=\frac{\sqrt{x^3}}{\sqrt{y}\left(\sqrt{x}-2\sqrt{y}\right)}-\frac{2x\left(x-1\right)}{\left(\sqrt{x}-2\sqrt{y}\right)\left(1+\sqrt{x}\right)\left(1-\sqrt{x}\right)}.\)
\(\left(1+\sqrt{x}\right)\left(1-\sqrt{x}\right)=1-x\)
\(A=\frac{\sqrt{x^3}-2x\sqrt{y}}{\sqrt{y}\left(\sqrt{x}-2\sqrt{y}\right)}=\frac{x\sqrt{x}-2x\sqrt{y}}{\sqrt{y}\left(\sqrt{x}-2\sqrt{y}\right)}=\frac{x\left(\sqrt{x}-2\sqrt{y}\right)}{\sqrt{y}\left(\sqrt{x}-2\sqrt{y}\right)}=\frac{x}{\sqrt{y}}\)
b) thay y=625 vào ta được
\(\frac{x}{\sqrt{625}}=\frac{x}{25}< 0.2\Leftrightarrow x< 5\)
vậy \(0< x< 5\)
1) 1/x-1/y
=y/xy-x/xy
=y-x/xy
= - (x-y)/xy
= -1 (vì x-y=xy)
2)
(x- 1/2)*(y+1/3)*(z-2)=0
=> x-1/2 = 0 hoac y+1/3=0 hoac z-2=0
th1 :x-1/2=0 => x=1/2
x+2=y+3=z+4
mà x=1/2 => y= -1/2 ; z=-3/2
th2: y+1/3=0
th3 : z-2=0
(tự làm nha)
1) Với x,y khác 0, Ta có
\(\frac{1}{x}-\frac{1}{y}=\frac{y-x}{xy}=-\left(\frac{x-y}{xy}\right)=-\left(\frac{xy}{xy}\right)=-1\)
Vậy \(\frac{1}{x}-\frac{1}{y}=-1\)
2) Ta có:
\(\left(x-\frac{1}{2}\right)\left(y+\frac{1}{3}\right)\left(z-2\right)=0\)
Trường hợp 1: x - 1/2 = 0 => x = 1/2 \(\Rightarrow\hept{\begin{cases}y=\frac{1}{2}+2-3=-\frac{1}{2}\\z=\frac{1}{2}+2-4=-\frac{3}{2}\end{cases}}\)
Trường hợp 2: y + 1/3 = 0 => y = -1/3 \(\Rightarrow\hept{\begin{cases}x=-\frac{1}{3}+3-2=\frac{2}{3}\\z=-\frac{1}{3}+3-4=-\frac{4}{3}\end{cases}}\)
Trường hợp 3: z - 2 = 0 => z = 2 \(\Rightarrow\hept{\begin{cases}x=2+4-2=4\\y=2+4-3=3\end{cases}}\)
Vậy......
a, 240 : y + 118 = 178
240 : y = 178 - 118
240 : y = 60
y = 240 : 60
y = 4
b, 2/9+1=1 (có j đó sai sai )
Ran Lili
a = 4 nha bạn
b thì mình cũng thấy sai
k tui nha
thank