Question

Tìm GTNN của:

A= x² - 2x +2

Answer 1

\(A=x^2-2x+2\)

\(A=x^2-2x+1+1\)

\(A=\left(x-1\right)^2+1\ge1\)

\(MinA=1\Leftrightarrow x-1=0\Leftrightarrow x=1\)

(Nhớ k cho mình với nhoa!)

Answer 2

\(A=x^2-2.1.x+1+2\Rightarrow A=\left(x-1\right)^2+1\ge1\)

\(\Rightarrow A_{min}=1\Leftrightarrow x-1=0\Rightarrow x=1\)

t i c k cho mình nha cảm ơn

Answer 3

Thank you so much! Tớ sẽ k cả 2.

Answer 4

=> A = x² - 2x + 1 + 1

=> A = (x - 1)² + 1 >= 1

=> A _MIN = 1 => x - 1 =  0 => x = 1

t i c k nhé!! 45465657678568578796898798796976965

Answer 5

\(A=x^2-2x+2\)

\(\Leftrightarrow A=x^2-2x+1+1\)

\(\Leftrightarrow A=\left(x-1\right)^2+1\)

Vì \(\left(x-1\right)^2\ge0\Rightarrow\left(x-1\right)^2+1\ge1\)

Biểu thức A đạt GTNN khi:

(x-1)²+1=1

<=>(x-1)²=0

<=>x-1=0

<=>x=1

Vậy A đạt GTNN là 1 khi x=1

Answer 6

okay , ai cũng có hết 1

Answer 7

e) \(\frac{6}{11}x=\frac{9}{2}y\Rightarrow\frac{x}{\frac{9}{2}}=\frac{y}{\frac{6}{11}}\Rightarrow\frac{-x}{-\frac{81}{5}}=\frac{y}{\frac{108}{55}}\)     (1)

\(\frac{9}{2}y=\frac{18}{5}f\Rightarrow\frac{y}{\frac{18}{5}}=\frac{f}{\frac{9}{2}}\Rightarrow\frac{y}{\frac{108}{55}}=\frac{f}{\frac{27}{11}}\)   (2)

Từ (1) và (2) => \(\frac{-x}{-\frac{81}{5}}=\frac{y}{\frac{108}{55}}=\frac{f}{\frac{27}{11}}\)

Áp dụng t/c của dãy tỉ số bằng nhau:

\(\frac{-x}{-\frac{81}{5}}=\frac{y}{\frac{108}{55}}=\frac{f}{\frac{27}{11}}=\frac{-x+y+f}{-\frac{81}{5}+\frac{108}{55}+\frac{27}{11}}=\frac{-120}{-\frac{648}{55}}=\frac{275}{27}\)

\(\Rightarrow x=\frac{275}{27}\cdot\frac{81}{5}=165\)

\(y=\frac{275}{27}\cdot\frac{108}{55}=20\)

\(f=\frac{275}{27}\cdot\frac{27}{11}=25\)

Answer 8

f) Đặt \(\frac{x}{12}=\frac{y}{9}=\frac{f}{5}=k\)

\(\Rightarrow x=12k\)

\(y=9k\)

\(f=5k\)

=> xyf = 20

<=> 12k * 9k * 5k = 20

540* k^3 = 20

k^3 = 1/27 

k= 1/3 

=> x= 12k = 12* 1/3 = 4

y= 9k = 9 * 1/3 = 3

f= 5k = 5* 1/3 = 5/3 

Answer 9

h) Ta có: 2x^3 - 1 = 15

2x^3 = 16

x^3 = 8 

x = 2

Thay x= 2 vào x+ 16/9 = y- 25/16 :

2+ 16/9 = y- 25/16 

34/9 = y- 25/16

y= 769/144

Thay x= 2 vào x+ 16/9 = f+ 9/25 :

2+ 16/9 = f+ 9/25

34/9 = f+ 9/25 

f= 769/225 

Vậy x= 2, y = 769/144, f= 769/225 

Answer 10

còn 2 ý nữa đâu

Answer 11

i) Đặt \(\frac{3}{5}x=\frac{2}{3}y=k\)

\(\Rightarrow x=k:\frac{3}{5}=\frac{5}{3}k\)

\(y=k:\frac{2}{3}=\frac{3}{2}k\)

\(\Rightarrow x^2-y^2=38\)

\(\Leftrightarrow\left(\frac{5}{3}k\right)^2-\left(\frac{3}{2}k\right)^2=38\)

\(\frac{25}{9}k^2\cdot\frac{9}{4}k^2=38\)

\(\frac{25}{4}k^4=38\)

\(k^4=\frac{152}{25}\)

\(k=\)

Rồi xong....tính ko ra.

Answer 12

\(\Rightarrow\)x^2 - 2x +1+1