Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Tk mình đi mọi người mình bị âm nè!
Ai tk mình mình tk lại cho
https://olm.vn/hoi-dap/detail/80277746933.html tham khảo bạn nha
a) \(M=x^3+x^2y-2x^2-xy-y^2+3y+x+2017\\= (x^3+x^2y-2x^2)-(xy+y^2-2y)+(x+y-2)+2019\\=x^2(x+y-2)-y(x+y-2)+(x+y-2)+2019\\=x^2.0-y.0+0+2019=2019\)
c) +) Với \(x + y + z = 0\) thì \(P = \dfrac{y+x}{y} \cdot \dfrac{z+y}z \cdot \dfrac{x + z}x = \dfrac{(-z)}{y} \cdot \dfrac{(-x)}z \cdot \dfrac{(-y)}x = -1\)
+) Với \(x + y + z \ne 0\)
Áp dụng tính chất dãy tỉ số bằng nhau :
\(\dfrac{y+z-x}x = \dfrac{z+x-y}y = \dfrac{x+y-z}z = \dfrac{y+z-x+z+x-y+x+y-z}{x+y+z} = \dfrac{x+y+z}{x+y+z} =1\)
Ta có \(\dfrac{y+z-x}x = 1 \iff y+z-x = x \iff y+z = 2x\)
Tương tự : \(z+x = 2y ; x + y = 2z\)
Kh đó \(P = \dfrac{y+x}{y} \cdot \dfrac{z+y}z \cdot \dfrac{x + z}x = \dfrac{2z}{y} \cdot \dfrac{2x}z \cdot \dfrac{2y}x = 8\)
Bài 1:
|\(x\)| = 1 ⇒ \(x\) \(\in\) {-\(\dfrac{1}{3}\); \(\dfrac{1}{3}\)}
A(-1) = 2(-\(\dfrac{1}{3}\))2 - 3.(-\(\dfrac{1}{3}\)) + 5
A(-1) = \(\dfrac{2}{9}\) + 1 + 5
A (-1) = \(\dfrac{56}{9}\)
A(1) = 2.(\(\dfrac{1}{3}\) )2- \(\dfrac{1}{3}\).3 + 5
A(1) = \(\dfrac{2}{9}\) - 1 + 5
A(1) = \(\dfrac{38}{9}\)
|y| = 1 ⇒ y \(\in\) {-1; 1}
⇒ (\(x;y\)) = (-\(\dfrac{1}{3}\); -1); (-\(\dfrac{1}{3}\); 1); (\(\dfrac{1}{3};-1\)); (\(\dfrac{1}{3};1\))
B(-\(\dfrac{1}{3}\);-1) = 2.(-\(\dfrac{1}{3}\))2 - 3.(-\(\dfrac{1}{3}\)).(-1) + (-1)2
B(-\(\dfrac{1}{3}\); -1) = \(\dfrac{2}{9}\) - 1 + 1
B(-\(\dfrac{1}{3}\); -1) = \(\dfrac{2}{9}\)
B(-\(\dfrac{1}{3}\); 1) = 2.(-\(\dfrac{1}{3}\))2 - 3.(-\(\dfrac{1}{3}\)).1 + 12
B(-\(\dfrac{1}{3};1\)) = \(\dfrac{2}{9}\) + 1 + 1
B(-\(\dfrac{1}{3}\); 1) = \(\dfrac{20}{9}\)
B(\(\dfrac{1}{3};-1\)) = 2.(\(\dfrac{1}{3}\))2 - 3.(\(\dfrac{1}{3}\)).(-1) + (-1)2
B(\(\dfrac{1}{3}\); -1) = \(\dfrac{2}{9}\) + 1 + 1
B(\(\dfrac{1}{3}\); -1) = \(\dfrac{20}{9}\)
B(\(\dfrac{1}{3}\); 1) = 2.(\(\dfrac{1}{3}\))2 - 3.(\(\dfrac{1}{3}\)).1 + (1)2
B(\(\dfrac{1}{3}\); 1) = \(\dfrac{2}{9}\) - 1 + 1
B(\(\dfrac{1}{3}\);1) = \(\dfrac{2}{9}\)