Question

(2x-5)^2-(x+2)^2=0

Answer 1

(2x - 5)² - (x + 2)² = 0

=> (2x - 5)² = (x + 2)²

=> 2x - 5 = x + 2 hoặc 2x - 5 = -(x + 2)

=> 2x - x = 2 + 5 hoặc 2x + x = -2 + 5

=> x = 7 hoặc 3x = 3

=> x = 7 hoặc x = 1

Answer 2

\(\Leftrightarrow3x^2-24x+21=0\)

\(\Rightarrow3\left(x^2-8x+7\right)=0\)

áp dụng delta ta có :

\(\Rightarrow x^2-8x+7=0\)

\(\Rightarrow\left(-8\right)^2-4\left(1.7\right)=36\)

\(\Rightarrow x_{1,2}=\frac{-b+-\sqrt{D}}{2a}=\frac{8+-\sqrt{36}}{2}\)

=>x=1 hoặc 7

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Answer 3

\(\Leftrightarrow3x^2-24x+21=0\)

\(\Rightarrow3\left(x^2-8x+7\right)=0\)

áp dụng delta ta có :

\(\Rightarrow x^2-8x+7=0\)

\(\Rightarrow\left(-8\right)^2-4\left(1.7\right)=36\)

\(\Rightarrow x_{1,2}=\frac{-b+-\sqrt{D}}{2a}=\frac{8+-\sqrt{36}}{2}\)

=>x=1 hoặc 7

Valentine vui vẻ