Câu hỏi của Nguyễn Hoàng Hà

Question

Tìm x, biết

2x3-50=0

x2-5x=-6

(2x-1)2-(3x+5)=0

d, 4x2-20x+25=0

e,(3x-1)2-(x-2)2=0

Mashiro Shiina · Accepted Answer

$2x^3-50=0$

$\Rightarrow2\left(x^3-25\right)=0$

$\Rightarrow x^3-25=0\Rightarrow x^3=25$

$\Rightarrow x=\sqrt[3]{25}$

$x^2-5x=-6$

$\Rightarrow x\left(x-5\right)=-6$

Xét ước

$\left(2x-1\right)^2-\left(3x+5\right)=0$

$\Rightarrow4x^2-4x+1-3x-5=0$

$\Rightarrow4x^2-4-7x=0$

$\Rightarrow4x^2-7x=4$

$\Rightarrow x\left(4x-7\right)=4$

Xét ước

$4x^2-20x+25=0$

$\Rightarrow\left(2x-5\right)^2=0$

$\Rightarrow2x=5\Rightarrow x=\dfrac{5}{2}$

$\left(3x-1\right)^2-\left(x-2\right)^2=0$

$\Rightarrow\left(3x-1\right)^2=\left(x-2\right)^2$

$\Rightarrow\left|3x-1\right|=\left|x-2\right|$

Xét dấu:vCâu trả lời: $2x^3-50=0$

$\Rightarrow2\left(x^3-25\right)=0$

$\Rightarrow x^3-25=0\Rightarrow x^3=25$

$\Rightarrow x=\sqrt[3]{25}$

$x^2-5x=-6$

$\Rightarrow x\left(x-5\right)=-6$

Xét ước

$\left(2x-1\right)^2-\left(3x+5\right)=0$

$\Rightarrow4x^2-4x+1-3x-5=0$

$\Rightarrow4x^2-4-7x=0$

$\Rightarrow4x^2-7x=4$

$\Rightarrow x\left(4x-7\right)=4$

Xét ước

$4x^2-20x+25=0$

$\Rightarrow\left(2x-5\right)^2=0$

$\Rightarrow2x=5\Rightarrow x=\dfrac{5}{2}$

$\left(3x-1\right)^2-\left(x-2\right)^2=0$

$\Rightarrow\left(3x-1\right)^2=\left(x-2\right)^2$

$\Rightarrow\left|3x-1\right|=\left|x-2\right|$

Xét dấu:v

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