Toán A) (2x + 1) mũ 3 = 125 B) (4x – 1) mũ 2 = 25 nhân 9 08/09/2021 By Elliana A) (2x + 1) mũ 3 = 125 B) (4x – 1) mũ 2 = 25 nhân 9
Đáp án: $\text{a) x = 2}$ $\text{b) x = 4}$ Giải thích các bước giải: $\text{(a (2x + 1)³ = 125}$ $\text{⇔ (2x + 1)³ = 5³}$ $\text{⇔ 2x + 1 = 5}$ $\text{⇔ 2x = 5 – 1}$ $\text{⇔ 2x = 4}$ $\text{⇔ x = 4 : 2}$ $\text{⇒ x = 2}$ $\text{Vậy: x = 2}$ $\text{b) (4x – 1)² = 25 . 9}$ $\text{(4x – 1)² = 3² . 5²}$ $\text{4x – 1 = 3 . 5}$ $\text{4x – 1 = 15}$ $\text{4x = 15 + 1}$ $\text{4x = 16}$ $\text{x = 16 : 4}$ $\text{x = 4}$ $\text{Vậy: x = 4}$ Trả lời
a) (2x + 1)³ = 125 ⇔ 2x + 1 = ∛125 ⇔ 2x + 1 = 5 ⇔ 2x = 4 ⇔ x = 2 b) (4x-1)² = 25.9 ⇔ 4x – 1 = √25 . √9 ⇔ 4x – 1 = 5 x 3 ⇔ 4x – 1 = 15 ⇔ 4x = 16 ⇔ x = 4 Trả lời
Đáp án:
$\text{a) x = 2}$
$\text{b) x = 4}$
Giải thích các bước giải:
$\text{(a (2x + 1)³ = 125}$
$\text{⇔ (2x + 1)³ = 5³}$
$\text{⇔ 2x + 1 = 5}$
$\text{⇔ 2x = 5 – 1}$
$\text{⇔ 2x = 4}$
$\text{⇔ x = 4 : 2}$
$\text{⇒ x = 2}$
$\text{Vậy: x = 2}$
$\text{b) (4x – 1)² = 25 . 9}$
$\text{(4x – 1)² = 3² . 5²}$
$\text{4x – 1 = 3 . 5}$
$\text{4x – 1 = 15}$
$\text{4x = 15 + 1}$
$\text{4x = 16}$
$\text{x = 16 : 4}$
$\text{x = 4}$
$\text{Vậy: x = 4}$
a) (2x + 1)³ = 125
⇔ 2x + 1 = ∛125
⇔ 2x + 1 = 5
⇔ 2x = 4
⇔ x = 2
b) (4x-1)² = 25.9
⇔ 4x – 1 = √25 . √9
⇔ 4x – 1 = 5 x 3
⇔ 4x – 1 = 15
⇔ 4x = 16
⇔ x = 4