3^{x + 4} + 3^x = 2214

⇔ 3^x . 3⁴ + 3^x = 2214

⇔ 3^x(3⁴ + 1) = 2214

⇔ 3^x . 82 = 2214

⇔ 3^x = 27

⇔ x = 3

nice

Sắp xếp theo đúng cột có phải ko bn

chuẩn

good luck

a. 6² : 4 + 2 . 5²                                              

= 36 : 4 + 2 . 25

= 9 + 50

= 59

b. 5 . 4² - 18 : 3²

= 5 . 16 - 18 : 9

= 80 - 2

= 78

c. 80 - (4 . 5² - 3 . 2²)

= 80 - (4 . 25 - 3 . 4)

= 80 - 100 +12

= -8

d. 450 - (4 . 5³ - 2² . 25)

= 450 - (4 . 125 - 4 . 25)

= 450 - 500 +100

= 50

e. 3² . 4² - (12 - 5)²

= 9 . 16 - (12² - 120 + 5²)

= 144 - 12² + 120 - 5²

= 144 - 144 + 120 - 25

= 120 - 25

= 95

f. 2⁴ . 5 + (13 - 4)² - 131

= 16 . 5 + 9² - 131

= 80 + 81 - 131

= 161 - 131

= 30

(6x - 7)⁴ = 625

⇔ 6x - 4 = 5

⇔ 6x = 9

⇔ x = \(\dfrac{9}{6}=\dfrac{3}{2}\)

Có 2 TH:

Nếu y \(\ge\) -2

<=> \(\left\{{}\begin{matrix}4x-\left(y+2\right)=3\\x+2\left(y+2\right)=3\end{matrix}\right.\) ⇔ \(\left\{{}\begin{matrix}4x-y-2=3\\x+2y+4=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x-y-2=3\\4x+8y+16=3\end{matrix}\right.\)

<=> \(\left\{{}\begin{matrix}9y+18=0\\4x-y=5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=-2\left(TM\right)\\x=0,75\end{matrix}\right.\)

Nếu y < -2

<=> \(\left\{{}\begin{matrix}4x-\left[-\left(y+2\right)\right]=3\\x+\left[2.-\left(y+2\right)\right]=3\end{matrix}\right.\) ⇔ \(\left\{{}\begin{matrix}4x+y+2=3\\x+\left(-2y\right)-4=3\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}4x+y=1\\x-2y=7\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x+y=1\\4x-8y=28\end{matrix}\right.\) ⇔ \(\left\{{}\begin{matrix}-9y=27\\4x+y=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=-3\left(TM\right)\\x=1\end{matrix}\right.\)

Vậy Ta có 2 TH: 

TH1: x = 0,75; y = -2

TH2: x = 1; y = -3

Ohhh, tui hiểu r.

x² - x + \(\dfrac{1}{4}\)

⇔ x² - 2.\(\dfrac{1}{2}\).x + \(\left(\dfrac{1}{2}\right)^2\)

⇔ \(\left(x^2-\dfrac{1}{2}\right)^2\)