a, <=> (x-2)²=25

<=>x-2=5 hoặc x-2=-5

<=>x=7 hoặc x=-3

c,<=>(x²)²-16=0

<=>(x²)²=16

<=>x²=4

<=>x=2 hoặc x=-2

HELP ME

câu b \(=\)4 chư ko fai 44

\(\frac{x-17}{1990}+\frac{x-21}{1986}+\frac{x+1}{1004}=4\)

\(\Leftrightarrow\left(\frac{x-17}{1990}-1\right)+\left(\frac{x-21}{1986}-1\right)+\left(\frac{x+1}{1004}-2\right)=0\)

\(\Leftrightarrow\frac{x-2007}{1990}+\frac{x-2007}{1986}+\frac{x-2007}{1004}=0\)

\(\Leftrightarrow\left(x-2007\right)\left(\frac{1}{1990}+\frac{1}{1986}+\frac{1}{1004}\right)=0\)

\(\Leftrightarrow x-2007=0\) (Vì \(\frac{1}{1990}+\frac{1}{1986}+\frac{1}{1004}>0\))

\(\Leftrightarrow x=2007\)

V...

a)

\(x^2-4x+4=25\)

\(\Leftrightarrow x^2-4x-21=0\)

\(\Leftrightarrow x^2+3x-7x-21=0\)

\(\Leftrightarrow x\left(x+3\right)-7\left(x+3\right)=0\)

\(\Leftrightarrow\left(x-7\right)\left(x+3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-3\end{matrix}\right.\)

b)

\(\dfrac{x-17}{1990}+\dfrac{x-21}{1986}+\dfrac{x+1}{1004}=4\)

\(\Leftrightarrow\dfrac{x-17}{1990}-1+\dfrac{x-21}{1986}-1+\dfrac{x+1}{1004}-2=4-1-1-2\)

\(\Leftrightarrow\dfrac{x-17-1990}{1990}+\dfrac{x-21-1986}{1986}+\dfrac{x+1-2008}{1004}=0\)

\(\Leftrightarrow\dfrac{x-2007}{1990}+\dfrac{x-2007}{1986}+\dfrac{x-2007}{1004}=0\)

\(\Leftrightarrow\left(x-2007\right)\left(\dfrac{1}{1990}+\dfrac{1}{1986}+\dfrac{1}{1004}\right)=0\)

\(\Leftrightarrow x-2007=0\) ( Vì: \(\dfrac{1}{1990}+\dfrac{1}{1986}+\dfrac{1}{1004}\ne0\))

\(\Leftrightarrow x=2007\)

c.

\(4^x-12.2^x+32=0\)

\(\Leftrightarrow\left(2^x\right)^2-12.2^x+36-4=0\)

\(\Leftrightarrow2^x-2.2^x.6+6^2-2^2=0\)
\(\Leftrightarrow\left(2^x-6\right)^2-2^2=0\)

\(\Leftrightarrow\left(2^x-6-2\right)\left(2^x-6+2\right)=0\)

\(\Leftrightarrow\left(2^x-8\right)\left(2^x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2^x-8=0\\2^x-4=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2^x=8\\2^x=4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=2\end{matrix}\right.\)

x−17/1990+x−21/1986+x+1 1004=4⇔x−17/1990−1+x−21/1986−1+x+1/1004−2=0

⇔x−2007/1990+x−2007/1986+x−2007/1004=0

⇔(x−2007)(1/1990+1/1986+1/1004)=0

⇔x−2007=0⇔x=2007

cách cut ơi tự giải đi, bạn hiền à

\(\dfrac{x-17}{1990}+\dfrac{x-21}{1986}+\dfrac{x+1}{1004}=4\)

\(\Rightarrow\left(\dfrac{x-17}{1990}-1\right)+\left(\dfrac{x-21}{1986}-1\right)+\left(\dfrac{x+1}{1004}-2\right)=0\)

\(\Rightarrow\dfrac{x-2007}{1990}+\dfrac{x-2007}{1986}+\dfrac{x-2007}{1004}=0\)

\(\Rightarrow\left(x-2007\right)\left(\dfrac{1}{1990}+\dfrac{1}{1986}+\dfrac{1}{1004}\right)=0\)

\(\Rightarrow x-2007=0\Rightarrow x=2007\)

Vậy x = 2007

\(\dfrac{x-17}{1990}+\dfrac{x-21}{1986}+\dfrac{x+1}{1004}=4\)

\(\Leftrightarrow\dfrac{x-17}{1990}-1+\dfrac{x-21}{1986}-1+\dfrac{x+1}{1004}-2=4-1-1-2\)

\(\Leftrightarrow\dfrac{x-17-1990}{1990}+\dfrac{x-21-1986}{1986}+\dfrac{x+1-2008}{1004}=0\)

\(\Leftrightarrow\dfrac{x-2007}{1990}+\dfrac{x-2007}{1986}+\dfrac{x-2007}{1004}=0\)

\(\Leftrightarrow\left(x-2007\right)\left(\dfrac{1}{1990}+\dfrac{1}{1986}+\dfrac{1}{1004}\right)=0\)

\(\Leftrightarrow x-2007=0\) ( Vì: \(\dfrac{1}{1990}+\dfrac{1}{1986}+\dfrac{1}{1004}\ne0\))

\(\Leftrightarrow x=2007\)

mk cũng đang định hỏi bài này nek^^