Đáp án không thôi nhá chứ giải mất tg lắm

a) \(6x^2-8x=2x\left(3x-4\right)\)

b) \(21x^2y^7-12x^5y^3=3x^2y^3\left(7y^4-4x^3\right)\)

c) \(4x^2y-6xy^2=2xy\left(2x-3y\right)\)

d) \(24x^2y-18xy^2=6xy\left(4x-3y\right)\)

e) \(9x^2y^2+12x^2y-15xy^2=3xy\left(3xy+4x-5y\right)\)

f) \(x\left(x+y\right)+y\left(-x-y\right)=x\left(x+y\right)-y\left(x+y\right)=\left(x+y\right)\left(x-y\right)\)

g) \(3\left(x+y\right)+x\left(x+y\right)=\left(x+y\right)\left(x+3\right)\)

h) \(3x\left(x-y\right)-6y\left(y-x\right)=3x\left(x-y\right)+6y\left(x-y\right)=3\left(x-y\right)\left(x+2y\right)\)

beautifully

excitedly

interesting

collected

arrangements

peacefully

excited

different

a,\(x^2-7x+6=x^2-x-6x+6\)

                       \(=x\left(x-1\right)-6\left(x-1\right)\)

                        \(=\left(x-6\right)\left(x-1\right)\)

a) x²-7x+6=(x²-x)-(6x-6)=x(x-1)-6(x-1)=(x-6)(x-1)

b) x²-6x+3=(x²-6x+9)-6=(x-3)²-\(\sqrt{6^2}\)=(x-3-\(\sqrt{6}\))(x-3+\(\sqrt{6}\))

c) x²-4x+3=(x²-x)-(3x-3)=x(x-1)-3(x-1)=(x-3)(x-1)

d) 3x²-5x+2=(3x²-3x)-(2x-2)=3x(x-1)-2(x-1)=(3x-2)(x-1)

e) 7x²-x-6=(7x²-7x)+(6x-6)=7x(x-1)+6(x-1)=(7x+6)(x-1)

f) 3x²-5x-8=(3x²+3x)-(8x+8)=3x(x+1)-8(x+1)=(3x-8)(x+1)

g) x²-6x+5=(x²-x)-(5x-5)=x(x-1)-5(x-1)=(x-5)(x-1)

h) x²-2x-3=(x²-2x+1)-4=(x-1)²-2²=(x-1-2)(x-1+2)=(x-3)(x+1)

i) x²-x-12=(x²+3x)-(4x+12)=x(x+3)-4(x+3)=(x-4)(x+3)

Lời giải:

ĐKĐB $\Rightarrow \frac{2}{c}=\frac{a+b}{ab}\Rightarrow c(a+b)=2ab$

Khi đó:

$\frac{a}{b}-\frac{a-c}{c-b}=\frac{a(c-b)-b(a-c)}{b(c-b)}=\frac{ac-ab-ab+bc}{b(c-b)}=\frac{c(a+b)-2ab}{b(c-b)}=\frac{2ab-2ab}{b(c-b)}=0$

$\Rightarrow \frac{a}{b}=\frac{a-c}{c-b}$ (đpcm) 

1 interested in travelling by plane

2 15 minutes riding his bike to school

3 is made by my mother everymorning

4 take care of her little brother

5 able to speak 2 languages when he was young

6 able to play the piano

7 is played all over VN

8 to play voleyball very well when he was young

9 to go fishing when he was young

10 way to the shopping mall

over

camping

was

couldn't

percussion

takes

look after

go around 

go through

wind

how long

for

do

45. The residents find heavy traffic annoying.

46. Mrs Brown is going to have the pipes checked by a plumber next Sunday.

47. This book, which consists of a list of endangered animals, is important.

48. I have difficulty improving my listening English skill.

49. In spite of not having time, they try to eat dinner together.

50. The police officer who gave me the directions how to get home was friendly.

51. They are looking forward to seeing their grandparents this weekend.

52. Unless you try your best, you won’t be successful.

Bài cuối mình không thấy rõ đề nhưng mình đoán là thế này bạn nhé.

a.

$ax-ay+bx-by=(ax-ay)+(bx-by)=a(x-y)+b(x-y)$

$=(a+b)(x-y)$

b. Trùng phần a

c. 

$x^2+xy+ax+ay=(x^2+xy)+(ax+ay)=x(x+y)+a(x+y)$

$=(x+a)(x+y)$

d.

$x^2y+xy^2-x-y=(x^2y+xy^2)-(x+y)$

$=xy(x+y)-(x+y)=(xy-1)(x+y)$

e.

$x^2y-xy^2-5x+5y=(x^2y-xy^2)-(5x-5y)$

$=xy(x-y)-5(x-y)=(x-y)(xy-5)$

f. Biểu thức không phân tích được thành nhân tử

g.

$x^2y-4x+xy^2-4y$

$=(x^2y+xy^2)-(4x+4y)=xy(x+y)-4(x+y)=(x+y)(xy-4)$
h.

$x^4+x^3+x+1=(x^4+x^3)+(x+1)$
$=x^3(x+1)+(x+1)=(x^3+1)(x+1)=(x+1)(x^2-x+1)(x+1)$

$=(x+1)^2(x^2-x+1)$

1 does this red dress cost

2 is this shirt

does this short cost

3 do these shoes cost

4 has brown backpack

5 how to get to the bus stop

6 to stay in bed

7 are cleaned by Nga everyday

8 is played with a bow

9 worked for that company for 10 years

10 15 minutes walking to school