41 - 2^x-1=9

<=> 2^x-1 = 32

<=> 2^x-1 = 2⁵

<=> x - 1 = 5

<=> x = 4

B1 : sử dụng quỳ tím

+, quỳ tím hóa đỏ : HCl , H2SO4 -> oxit axit (1)

+) quỳ tím hóa xanh : KOH ->oxit bazo (2)

+) quỳ tím ko chuyển màu : NaNO3 -> muối (3)

B2: cho lần lượt các dd ở nhóm (1) t/d vs BaCl2 , nếu thấy hiện tượng kết tủa trắng là H2SO4 , còn lại là HCl

PTHH : H2SO4 + BaCl2 -> 2HCl + BaSO4

a, hàm số đã cho đồng biến <=> \(\dfrac{m-1}{m-4}>0\)

                                              <=>\(\left[{}\begin{matrix}\left\{{}\begin{matrix}m-1>0\\m-4>0\end{matrix}\right.\\\left\{{}\begin{matrix}m-1< 0\\m-4< 0\end{matrix}\right.\end{matrix}\right.< =>\left[{}\begin{matrix}\left\{{}\begin{matrix}m>1\\m>4\end{matrix}\right.\\\left\{{}\begin{matrix}m< 1\\m< 4\end{matrix}\right.\end{matrix}\right.\)

                                                =>m>4 hoặc m<1

ĐKXĐ : \(m\ne\dfrac{1}{2}\)

Đặt : \(2x-1=\left(2m-1\right)x+3m\) (1)

Để 2 đường thẳng trên cắt nhau tại 1 điểm trên trục hoành thì ta thay x=0 vào (1), được

\(-1=3m\) <=>\(m=\dfrac{-1}{3}\) (thỏa mãn )

Kirito-Kun \(4x^2-4x+4\) đâu p hằng đẳng thức đâu

1, \(\left(2\sqrt{x}+3\right)\left(2\sqrt{x}-1\right)-\sqrt{x}\left(-3+4\sqrt{x}\right)=0\)

<=>\(4x-2\sqrt{x}+6\sqrt{x}-3+3\sqrt{x}-4x=0\)

<=>\(7\sqrt{x}=3\)

<=>\(\sqrt{x}=\dfrac{3}{7}\)

<=>\(x=\dfrac{9}{49}\)

2) \(\dfrac{1}{5}\sqrt{25x+50}-5\sqrt{x+2}+\sqrt{9x+18}+9=0\)

<=>\(\sqrt{x+2}-5\sqrt{x+2}+3\sqrt{x+2}=-9\)

<=>\(-\sqrt{x+2}=-9\)

<=>\(\sqrt{x+2}=9\)

<=>\(x+2=81\)

<=>\(x=79\)

3) \(\sqrt{4x^2-4x+4}=7x-11\)

<=>\(4x^2-4x+4=49x^2-154x+121\)

<=>\(-45x^2+150x-117=0\)

<=>\(x=\dfrac{25+2\sqrt{10}}{15}\) hoặc \(x=\dfrac{25-2\sqrt{10}}{15}\)

.

\(\dfrac{4}{\sqrt{5}-9}-\dfrac{4}{\sqrt{5}+2}=\dfrac{4\sqrt{5}+8-4\sqrt{5}+36}{\left(\sqrt{5}-9\right)\left(\sqrt{5}+2\right)}=\dfrac{44}{5+2\sqrt{5}-9\sqrt{5}-18}=\dfrac{-44}{7\sqrt{5}+13}\)

I.       Choose the word or phrase (a, b, c or d) that best fits the blank space in each sentence.

1.      The trip to the countryside was very _____. We all enjoyed ourselves a lot.

a. interest                      b. interested                     c. interesting                   d. interestingly

2.      They had a good time together before _____ home late in the evening.

a. go                              b. went                             c. to go                           d. going

3.      Liz _____ a lot of photos of her friends and the countryside.

a. made                         b. took                             c. turned                         d. did

4.      Everyone felt very tired and hungry, _____ they stopped to have a snack.

a. so                              b. but                               c. even though                d. if

5.      She said she would show the photos _____ her parents later.

a. to                               b. for                                c. with                            d. in

6.      Van is now living with the Parkers _____ a farm outside Columbus, Ohio.

a. in                               b. with                             c. of                                d. on

7.      The Parker family treats Van very well, so he feels _____ a member of the family.

a. about                         b. as                                 c. like                              d. for

8.      “Did you wait for him very long?” “Yes. I _____ to bed until 12:00 p.m.”

a. went                          b. did go                          c. had gone                     d. didn’t go

9.      “How long has Jimmy been here?” “He _____ two days ago.”

a. has been                    b. came                            c. would be                     d. had been

10.  The member of the family ate hamburgers while Peter _____ baseball.

a. is playing                  b. plays                            c. was playing                d. has been playing