Question

Câu 1: So sánh \(\sqrt{7}+\sqrt{5}\)và 7

Câu 2 : Tìm x biết: (3x-7)²⁰⁰⁷=(3x-7)²⁰⁰⁵

Answer 1

(3x - 7)²⁰⁰⁷ = (3x - 7)²⁰⁰⁵

=> (3x - 7)²⁰⁰⁷ - (3x - 7)²⁰⁰⁵ = 0

=> (3x - 7)²⁰⁰⁵ [(3x - 7)² - 1] = 0

=> (3x - 7)²⁰⁰⁵ = 0 hoặc (3x - 7)² - 1 = 0

+) (3x - 7)²⁰⁰⁵ = 0

=> 3x - 7 = 0

=> 3x = 7

=> x = 7/3

+) (3x - 7)² - 1 = 0

=> (3x - 7)² = 1

=> 3x - 7 = 1  => 3x = 8 => x = 8/3

     3x - 7 = -1 => 3x = 6 => x = 2

Vậy: x \(\in\){-7/3;8/3;2

Answer 2

3x-7=1=>x=2\(\frac{2}{3}\)

3x-7=0=>x=2\(\frac{1}{3}\)