TH1 2x-7>0thi x=-12

TH2 2x-7<0 thu x=-2,4

mk k biết đ k nữa lm bừa thui

ĐK: \(x\ge\dfrac{5}{3}\)

Ta có: \(\sqrt{2x+5}=2+\sqrt{3x-5}\)

      \(\Leftrightarrow2x+5=4+3x-5+4\sqrt{3x-5}\)

      \(\Leftrightarrow6-x=4\sqrt{3x-5}\)                    ĐK: x≤6

      \(\Leftrightarrow36-12x+x^2=48x-80\)

      \(\Leftrightarrow x^2-60x+116=0\)

      \(\Leftrightarrow\left(x-2\right)\left(x-58\right)=0\)

      \(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=58\end{matrix}\right.\)

So với điều kiện thì phương trình có nghiệm duy nhất là x = 2

\(ĐK:x\ge\dfrac{5}{3}\\ PT\Leftrightarrow\left(\sqrt{2x+5}-3\right)-\left(\sqrt{3x-5}-1\right)=0\\ \Leftrightarrow\dfrac{2x-4}{\sqrt{2x+5}+3}-\dfrac{3x-6}{\sqrt{3x-5}+1}=0\\ \Leftrightarrow\left(x-2\right)\left(\dfrac{2}{\sqrt{2x+5}+3}-\dfrac{3}{\sqrt{3x-5}+1}\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2\left(tm\right)\\\dfrac{2}{\sqrt{2x+5}+3}=\dfrac{3}{\sqrt{3x-5}+1}\left(1\right)\end{matrix}\right.\)

\(\left(1\right)\Leftrightarrow2\sqrt{3x-5}+2=3\sqrt{2x+5}+9\\ \Leftrightarrow2\sqrt{3x-5}=7+3\sqrt{2x+5}\\ \Leftrightarrow4\left(3x-5\right)=49+9\left(2x+5\right)+42\sqrt{2x+5}\\ \Leftrightarrow12x-20=49+18x+45+42\sqrt{2x+5}\\ \Leftrightarrow-6x-144=42\sqrt{2x+5}\)

Vì \(x\ge\dfrac{5}{3}>0\Leftrightarrow-6x-144< 0< 42\sqrt{2x+5}\)

Do đó (1) vô nghiệm

Vậy PT có nghiệm \(x=2\)

`1,[(-3).3+5]-26=-2x-3`

`=>(-9+5)-26=-2x-3`

`=>-4-26=-2x-3`

`=>-30=-2x-3`

`=>-2x=-27`

`=>x=27/2`

Vậy `x=27/2`

`2)-[(-35)-3]=2x-2`

`=>-(-38)=2x-2`

`=>38=2x-2`

`=>2x=40`

`=>x=20`

Vậy `x=20`

1) \(\left[\left(-3\right)\cdot3+5\right]-26=-2x-3\\ \Rightarrow-9+5-26=-2x-3\\ \Rightarrow-2x=-9+5-26+3\\ \Rightarrow-2x=-27\\ \Rightarrow x=\dfrac{27}{2}\)

Vậy \(x=\dfrac{27}{2}\)

2) \(-\left[\left(-35\right)-3\right]=2x-2\\ \Rightarrow2x-2=-\left(-38\right)\\ \Rightarrow2x=38+2\\ \Rightarrow2x=40\\ \Rightarrow x=20\)

Vậy \(x=20\)

1) Ta có: \(\left[\left(-3\right)\cdot3+5\right]-26=-2x-3\)

\(\Leftrightarrow-2x-3=-4-26\)

\(\Leftrightarrow-2x-3=-30\)

\(\Leftrightarrow-2x=-27\)

hay \(x=\dfrac{27}{2}\)

Vậy: \(x=\dfrac{27}{2}\)

2) Ta có: \(-\left[\left(-35\right)-3\right]=2x-2\)

\(\Leftrightarrow2x-2=-\left(-38\right)\)

\(\Leftrightarrow2x-2=38\)

\(\Leftrightarrow2x=40\)

hay x=20

Vậy: x=20

b)(2x - 1)^2 - (2x + 5) (2x - 5 ) = 18

4x 2 -4x+1-4x 2+25=18

26-4x=18

4x=8

x=2

a,27x-18=2x-3x^2

<=> 3x^2-2x+27-18x=0

<=> 3x^2-20x+27=0

\(\Delta\)= 20^2-4-12.27

tính \(\Delta\)rồi tìm x1 ,x2

â)\(9\left(3x-2\right)=x\left(2-3x\right)\)

\(\Leftrightarrow27x-18=2x-3x^2\)

\(\Leftrightarrow27x-18-2x+3x^2=0\)

\(\Leftrightarrow3x^2+25x-18=0\)

\(\Leftrightarrow3x^2+27x-2x-18=0\)

\(\Leftrightarrow\left(3x-2\right)\left(x+9\right)=0\)

       \(\Rightarrow\orbr{\begin{cases}3x-2=0\\x+9=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{2}{3}\\x=-9\end{cases}}\)

b)\(\left(2x-1\right)^2-\left(2x+5\right)\left(2x-5\right)=18\)

\(\Leftrightarrow4x^2-4x+1-4x^2+25=18\)

\(\Leftrightarrow26-4x=18\)

 \(\Leftrightarrow4x=8\)

      \(\Rightarrow x=2\)

c)\(5x\left(x-5\right)-2x+10=0\)

\(\Leftrightarrow5x^2-10x-2x+10=0\)

\(\Leftrightarrow5x^2-12x+10=0\)

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

\(\Leftrightarrow x^2-6x+9-7=0\)

\(\Leftrightarrow\left(x-3\right)^2=7\)

       \(\Rightarrow\orbr{\begin{cases}x-3=\sqrt{7}\\x-3=-\sqrt{7}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\sqrt{7}+3\\x=-\sqrt{7}+3\end{cases}}\)

d)\(x^2-5=0\)

\(\Leftrightarrow x^2=5\)

    \(\Rightarrow x=\sqrt{5};-\sqrt{5}\)

e)\(x^3+5x^2-4x-20=0\)

\(\Leftrightarrow x^3-2x^2+7x^2-14x+10x-20=0\)

\(\Leftrightarrow x^2\left(x-2\right)+7x\left(x-2\right)+10\left(x-2\right)=0\)

\(\Leftrightarrow\left(x^2+7x+10\right)\left(x-2\right)=0\)

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

\(\Leftrightarrow\left(x^2-4\right)\left(x+5\right)=0\)

      \(\Rightarrow\orbr{\begin{cases}x+5=0\\x^2-4=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=-5\\x^2=4\end{cases}\Rightarrow}\orbr{\begin{cases}x=-5\\x=-2;2\end{cases}}\)

Lời giải:

a. $9x^2-16-(3x-4)(2x+5)=0$

$\Leftrightarrow [(3x)^2-4^2]-(3x-4)(2x+5)=0$

$\Leftrightarrow (3x-4)(3x+4)-(3x-4)(2x+5)=0$

$\Leftrightarrow (3x-4)(3x+4-2x-5)=0$

$\Leftrightarrow (3x-4)(x-1)=0$

$\Leftrightarrow 3x-4=0$ hoặc $x-1=0$

$\Leftrightarrow x=\frac{4}{3}$ hoặc $x=1$.

b.

$x^2+4x=12$

$\Leftrightarrow x^2+4x-12=0$

$\Leftrightarrow (x^2-2x)+(6x-12)=0$

$\Leftrightarrow x(x-2)+6(x-2)=0$

$\Leftrightarrow (x-2)(x+6)=0$

$\Leftrightarrow x-2=0$ hoặc $x+6=0$

$\Leftrightarrow x=2$ hoặc $x=-6$

c.

$x^2-2x=35$

$\Leftrightarrow x^2-2x-35=0$

$\Leftrightarrow (x^2+5x)-(7x+35)=0$

$\Leftrightarrow x(x+5)-7(x+5)=0$

$\Leftrightarrow (x+5)(x-7)=0$

$\Leftrightarrow x+5=0$ hoặc $x-7=0$

$\Leftrightarrow x=-5$ hoặc $x=7$

 Today I'd to describe my home garden, which I think is a beautiful one and which I very much. The garden is part of my home's backyard, and my house is located in the suburbs, about a 1-hour drive from the city of San Francisco. There is a big tree right in the middle of my garden, which is surrounded by a hot tub, a small water fountain, several bushes, a section for vegetables, and different kinds of flowers.

 This garden was actually one of the reasons why my wife and I chose to buy our house because it had been beautifully maintained by the previous owner’s gardener and landscaper. It’s been only 1 year since we bought the house and now we are taking care of the garden ourselves. Even though we are not experts in gardening, we still try our best to plant things that we , such as roses and tulips, and we even grow our own tomatoes.

Whenever family and friends come to visit us, we invite them to have a relaxing time in our hot tub, and enjoy the view. So in other words, our garden has also become a kind of resort! It definitely requires lots of hard work to properly maintain the garden, but it gives us a great sense of accomplishment to “decorate” it the way we .

All in all, the garden is one of the best features of my home and it is a place where I can relax after a long day of work or during the weekends.

Inasmuch as my grandfather is a pensioner, he has taken up gardening. the garden is a very beautiful landscape. It is separated from the outside by a hedge. It is located at the backyard of our house. At the entry of the garden there is a pretty pergola with little climbers on it. At the center of the garden stands a giant shade tree. Patio furniture consisting of wicker table and chairs is placed underneath this tree. I usually sit here playing chess with my grandfather. He plants several kinds of flowers rose, gerbera, narcissus, cockscomb,... to make the garden colorful. He also spends a corner of the garden for vegetables supporting our meals. In other corner he puts some gardening tools a watering can, spades, forks, clippers,... the thing I the most is the birdhouse where plenty of birds come to nest. Everyday afterschool my grandfather together with me usually does the gardening works to keep the garden as before. It is of paramount importance to me and I love this garden so much.

câu trên ko nhìn rõ

6. D

7. C

tỉ số giữa A và B là:2:4=1/2

Sơ đồ:

a:/.../

b:/.../.../ tổng 18

a là:18:(2+1)=6

b là 18-6=12

Ta có: a/2=b/4

\(\frac{a+b}{2+4}\)=\(\frac{18}{6}\)=3

suy ra: a=3.2=6

b=3.4=12

Ta có a/b =2/4

=>a×4=b×2

=>a.   =b×2÷4

=> a.  =b×2/4

Thay vào ta có

b×2/4+b=18

b×(1/2+1)=18

b×3/2=18

b.       =18÷3/2

b.       =12

a+12=18

a.      =18-12

a.      =6

Vậy a=6 và b=12