G(x)=0

=> 4x-7-x-14 =0 => 3x -21= 0

=> x=7

bạn ơi x=7

Bài 2 : 

a, \(x^2-4x+4+1=\left(x-2\right)^2+1\ge1\)

Dấu ''='' xảy ra khi x = 2 

b, Ta có \(\left(x+1\right)^2+10\ge10\Rightarrow\dfrac{-100}{\left(x+1\right)^2+10}\ge-\dfrac{100}{10}=-10\)

Dấu ''='' xảy ra khi x = -1 

 Bài 1 : 

a, Ta có \(A\left(x\right)=x^2-4x+4=0\Leftrightarrow\left(x-2\right)^2=0\Leftrightarrow x=2\)

b, \(B\left(x\right)=x^2\left(2x+1\right)+\left(2x+1\right)=\left(x^2+1>0\right)\left(2x+1\right)=0\Leftrightarrow x=-\dfrac{1}{2}\)

c, \(C\left(x\right)=\left|2x-3\right|=\dfrac{1}{3}\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{1}{3}+3=\dfrac{10}{3}\\2x=-\dfrac{1}{3}+3=\dfrac{8}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{3}\\x=\dfrac{4}{3}\end{matrix}\right.\)

a: P(x)=0

=>4x-7-x-14=0

=>3x-21=0

=>x=7

b: x^2+x=0

=>x(x+1)=0

=>x=0; x=-1

a) Ta có: \(x^2-8x+7=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-7\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=7\end{matrix}\right.\)

b) Ta có: \(x^2+x-20=0\)

\(\Leftrightarrow\left(x+5\right)\left(x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=4\end{matrix}\right.\)

c) Ta có: \(3x^2+4x-4=0\)

\(\Leftrightarrow3x^2+6x-2x-4=0\)

\(\Leftrightarrow3x\left(x+2\right)-2\left(x+2\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(3x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{2}{3}\end{matrix}\right.\)

d) Ta có: \(3x^2-4x-7=0\)

\(\Leftrightarrow3x^2-7x+3x-7=0\)

\(\Leftrightarrow\left(3x-7\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{3}\\x=-1\end{matrix}\right.\)

e) Ta có: \(5x^2-16x+3=0\)

\(\Leftrightarrow5x^2-15x-x+3=0\)

\(\Leftrightarrow\left(x-3\right)\left(5x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\)

f) Ta có: \(x^2+3x-10=0\)

\(\Leftrightarrow x^2+5x-2x-10=0\)

\(\Leftrightarrow\left(x+5\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

a)

\(x^2-8x+7=0\text{⇔}\text{⇔}x^2-7x-x-7=\left(x-7\right)\left(x-1\right)=0\text{⇔}\left[{}\begin{matrix}x=1\\x=7\end{matrix}\right.\)

Vậy nghiệm của đa thức : \(S=\left\{1;7\right\}\)

c)

\(3x^2+4x-4=0\text{⇔}3x^2+6x-2x-4=\left(3x-2\right)\left(x+2\right)=0\text{⇔}\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-2\end{matrix}\right.\)

Vậy nghiệm của đa thức : \(S=\left\{\dfrac{2}{3};-2\right\}\)

b)

\(x^2+x-20=0⇔\left(x-4\right)\left(x+5\right)=0\text{⇔}\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)

d)

\(3x^2-4x-7=0\text{⇔}\left(3x-7\right)\left(x+1\right)=0\text{⇔}\left[{}\begin{matrix}x=-1\\x=\dfrac{7}{3}\end{matrix}\right.\)

e)

\(5x^2-16x+3\text{⇔}\left(x-3\right)\left(5x-1\right)=0\text{⇔}\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\)

f)

\(x^2+3x-10=0\text{⇔}\left(x-2\right)\left(x+5\right)=0\text{⇔}\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\)

\(\)

b: 1/2x-4=0

=>1/2x=4

hay x=8

a: x+7=0

=>x=-7

e: 4x²-81=0

=>(2x-9)(2x+9)=0

=>x=9/2 hoặc x=-9/2

g: x²-9x=0

=>x(x-9)=0

=>x=0 hoặc x=9

a)\(x+7=0=>x=-7\)

b)\(\dfrac{1}{2}x-4=0=>\dfrac{1}{2}x=4=>x=8\)

c)\(-8x+20=0=>-8x=-20=>x=\dfrac{5}{2}\)

d)\(x^2-100=0=>x^2=100=>\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)

e)\(4x^2-81=0=>4x^2=81=>x^2=\dfrac{81}{4}=>\left[{}\begin{matrix}x=\dfrac{9}{2}\\x=-\dfrac{9}{2}\end{matrix}\right.\)

f)\(x^2-7=0=>x^2=7=>x=\sqrt{7}\)

g)\(x^2-9x=0=>x\left(x-9\right)=0=>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)

a: x+7=0

nên x=-7

b: x-4=0

nên x=4

c: -8x+20=0

=>-8x=-20

hay x=5/2

d: x²-100=0

=>(x-10)(x+10)=0

=>x=10 hoặc x=-10

a) x +7 =0

=>x = -7

b) x - 4 =0=>x = 4

c) -8x + 20 = 0 =>-8x =-20 =>\(x=-\dfrac{20}{-8}=\dfrac{5}{2}\)

d)\(x^2-100=0=>x^2=100>\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)

e)\(4x^2-81=0=>4x^2=81=>x^2=\dfrac{81}{4}=>\left[{}\begin{matrix}x=\dfrac{9}{2}\\x=-\dfrac{9}{2}\end{matrix}\right.\)

f)\(x^2-7=0=>x^2=7=>x=\sqrt{7}\)

g)\(x^2-9x=0=>x\left(x-9\right)=0=>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)

H)\(x^3+3x=0=>x\left(x^2 +3\right)=0=>\left[{}\begin{matrix}x=0\\x^2=-3\left(vl\right)\end{matrix}\right.\)

a: Đặt 2x-8=0

=>2x=8

hay x=4

b: Đặt 1/2x²+3/4x=0

=>x(1/2x+3/4)=0

=>x=0 hoặc x=-3/2

a, \(2x-8=0\Leftrightarrow x=4\)

b, \(\dfrac{1}{2}x\left(x+\dfrac{3}{2}\right)=0\Leftrightarrow x=0;x=-\dfrac{3}{2}\)

4:

a: f(x)=0

=>-x-4=0

=>x=-4

b: g(x)=0

=>x^2+x+4=0

Δ=1^2-4*1*4=1-16=-15<0

=>g(x) ko có nghiệm 

c: m(x)=0

=>2x-2=0

=>x=1

d: n(x)=0

=>7x+2=0

=>x=-2/7

Phần nào bạn ko nhìn thấy thì bảo mk nhé