sao nhieu bai kho hieu trong violympic toan tieng anh the nhi
ai cho minh dap an vong 7 toan tieng anh vong 2 va 3 di
de thi violympic toan tieng anh lop 4 vong 9
the sum of two consecutive even numbers is 3026.find the smaller number
ai co nick toan tieng anh lop 6 den vong 7 cho mk mot nick nha
ai biet de thi tieng anh va toan lop 6 chua
ghi lai ho minh kem theo dap an
FIND THE GREATEST NATURAL m SUCH THAT :
If x - y - z = 0 and x + 2y - 10z = 0, z ≠ 0 then the value of is ............
\(\left\{\begin{matrix}x-y-z=0\left(1\right)\\x+2y-10z=0\left(2\right)\end{matrix}\right.\)
Lấy (1) - (2), ta có:
\(-3y+9z=0\Leftrightarrow-3\left(y-z\right)=0\)
\(\Rightarrow y-z=0\)
\(\Rightarrow y=-z\)
Thay y=-z vào (1), ta có:
\(x-\left(-z\right)-z=0\Rightarrow x=0\)
Thay x=0 vào B, ta được B=0 (tử bằng 0)
\(\left\{\begin{matrix}x-y-z=0\left(1\right)\\x+2y-10z=0\left(2\right)\end{matrix}\right.\)
Lấy (1) - (2), ta được:
-3y+9z=0
-3(y-z)=0
=> y-z=0=>y=z
Thay y=z vào (1), ta có:
x-z-z=0<=>x-2z=0=>x=2z
Thay, x=2z,y=z vào B, ta có:
\(B=\frac{2x^2+4xy}{y^2+z^2}\)
\(B=\frac{2.\left(2z\right)^2+4.2z.z}{z^2+z^2}=\frac{16z^2}{2z^2}=8\)
\(\begin{cases} x-y-z=0 (1)\\ x+2y-10z=0(2) \end{cases}\)
Lấy (1)-(2) ta được:-3y+9z=0
\(\Leftrightarrow \) y=3z thay vào (1) được : x=4z
Khi đó: B=8
Tìm K,biết
Given the rectangle ABCD and the triangle BEC. Find the value of x such that the ratio of the area of the rectangle to the area of the triangle BEC is 7:3.
Answer: x = ....... cm.
ta co ti so:
\(\frac{S_{abcd}}{S_{bec}}=\frac{7}{3}\Leftrightarrow\frac{ab.bc}{\frac{x.bc}{2}}=\frac{7}{3}\Leftrightarrow\frac{2ab}{x}=\frac{7}{3}\)
\(\Leftrightarrow\)\(\Leftrightarrow\frac{2.7}{x}=\frac{7}{3}\Leftrightarrow\frac{2}{x}=\frac{1}{3}\Leftrightarrow x=6\)
If x - y - z = 0 and x + 2y - 10z = 0, z ≠ 0 then the value of is ............
\(\left\{{}\begin{matrix}x-y-z=0\\x+2y-10z=0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}y=3z\\x=y+z=4z\\x+2y=10z\end{matrix}\right.\)
\(B=\dfrac{2x^2+4xy}{y^2+z^2}=\dfrac{2x\left(x+2y\right)}{9z^2+z^2}=\dfrac{2.4z.10z}{10.z^2}=8\)
Find K such that:
= 1 nha
mik chuc ban hoc gioi ha