Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(5X\left(X-2020\right)+X=2020\)
\(\Leftrightarrow5X^2-10100X+X=2020\)
\(\Leftrightarrow5X^2-10099X=2020\)
\(\Leftrightarrow5X^2-10099X-2020=0\)
\(\Leftrightarrow5X^2-10100X+x-2020=0\)
\(\Leftrightarrow5X\left(X-2020\right)+X-2020=0\)
\(\Leftrightarrow\left(X-2020\right)\left(5X+1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2020\\x=-\frac{1}{5}\end{cases}}\)
\(4\left(x-5\right)^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)\right]^2-\left(2x+1\right)^2=0\)
\(\Leftrightarrow\left[2\left(x-5\right)-2x-1\right]\left[2\left(x-5\right)+2x+1\right]=0\)
\(\Leftrightarrow\left(2x-10-2x-1\right)\left(2x-10+2x+1\right)=0\)
\(\Leftrightarrow-11\left(4x-9\right)=0\)
\(\Leftrightarrow x=\frac{9}{4}\)
a: \(2x^4-3x^3+4x+1⋮x^2-1\)
\(\Leftrightarrow2x^4-2x^2-3x^3+3x+2x^2-2+x+3⋮x^2-1\)
\(\Leftrightarrow x+3⋮x^2-1\)
\(\Leftrightarrow x^2-9⋮x^2-1\)
\(\Leftrightarrow x^2-1\in\left\{1;-1;2;-2;4;-4;8;-8\right\}\)
\(\Leftrightarrow x\in\left\{\sqrt{2};-\sqrt{2};0;\sqrt{3};-\sqrt{3};\sqrt{5};-\sqrt{5};3;-3\right\}\)
b: \(x^5+2x^4+3x^2+x-3⋮x^2+1\)
\(\Leftrightarrow x^5+x^3+2x^4+2x^2-x^3-x+x^2+1+2x-4⋮x^2+1\)
\(\Leftrightarrow2x-4⋮x^2+1\)
\(\Leftrightarrow4x^2-16⋮x^2+1\)
\(\Leftrightarrow4x^2+4-20⋮x^2+1\)
\(\Leftrightarrow x^2+1\in\left\{1;2;4;5;10;20\right\}\)
hay \(x\in\left\{0;1;-1;\sqrt{3};-\sqrt{3};2;-2;3;-3;\sqrt{19};-\sqrt{19}\right\}\)
\(A=5x\left(4x^2-2x+1\right)-2x\left(10x^2-5x-2\right)\)
\(=20x^3-10x^2+5x-20x^3+10x^2+4x\)
\(=9x=9.15=135\)
\(\left(9x-1\right)^2-2\left(9x-1\right)\left(5x-1\right)+\left(5x-1\right)^2=\left(9x-1-5x+1\right)^2=\left(14x\right)^2=196x^2\)
bài 1.2 làm như sau:
x3 - 3x2+3x-1=0
x3-3x2.1+3x.12-13=0
áp dụng HĐT số 5 trong sách ta có
(x-1)3=0
=> x-1=0
x=1
Bài 2: a) \(3x^3-3x=0\Leftrightarrow3x\left(x^2-1\right)=0\Leftrightarrow\orbr{\begin{cases}x=0\\x=\pm1\end{cases}}\)
b) \(x^2-x+\frac{1}{4}=0\Leftrightarrow x^2-2.\frac{1}{2}+\left(\frac{1}{2}\right)^2=0\Leftrightarrow\left(x-\frac{1}{2}\right)^2=0\)
\(\Leftrightarrow x-\frac{1}{2}=0\Leftrightarrow x=\frac{1}{2}\)