1, ($\frac{x}{1}$ – $\frac{1}{4}$)² = $\frac{1}{4}$
2, $2^{x}$ + $2^{x+3}$ = 144
3, $81^{-2x}$.$27^{x}$ = $9^{5}$
1, ($\frac{x}{1}$ – $\frac{1}{4}$)² = $\frac{1}{4}$ 2, $2^{x}$ + $2^{x+3}$ = 144 3, $81^{-2x}$.$27^{x}$ = $9^{5}$
By Adalyn
By Adalyn
1, ($\frac{x}{1}$ – $\frac{1}{4}$)² = $\frac{1}{4}$
2, $2^{x}$ + $2^{x+3}$ = 144
3, $81^{-2x}$.$27^{x}$ = $9^{5}$
Đáp án:
Giải thích các bước giải:
1.
(x/1 – 1/4)² = 1/4
⇔ (x/1 – 1/4)² = (±1/2)²
⇔ x – 1/4 = 1/2 ⇔ x= 3/4
Hoặc x -1/4 = -1/2 ⇔ x= -1/4
Vậy x ∈ {3/4; -1/4}
2.
2^x + 2^x+3 = 144
⇔ 2^x + 2^x . 2^3 = 144
⇔ 2^x . (1+8) = 144
⇔ 2^x . 9 =144
⇔ 2^x = 16
⇔ 2^x = 2^4
⇔ x=4
Vậy x=4
`1)`
`( \frac{x}{1} – \frac{1}{4} )^2 = \frac{1}{4}`
`=>` \(\left[ \begin{array}{l} \frac{x}{1} – \frac{1}{4} = \frac{1}{2}\\\frac{x}{1} – \frac{1}{4} = – \frac{1}{2}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l} x = \frac{3}{4}\\\x = – \frac{1}{4}\end{array} \right.\)
`2)`
`2^x + 2^{x+3} = 144`
`=> 2^x(1 + 2^3 ) = 144`
`=> 2^x . 9 = 144`
`=> 2^x = 16`
`=> x = 4`
3) Chưa nghĩ ra