A=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}\)

=\(\dfrac14+\dfrac19\)

=\(\dfrac{9}{36}+\dfrac{4}{36}\)

=\(\dfrac{13}{36}\)

Vậy A=\(\dfrac{13}{36}\)

237 + 233 + 446 + 444

= (237 + 233) + ( 446 + 444)

= 470 + 890

= 1360

Có môn toán nha bạn!

Hai đơn thức đồng dạng có hệ số khác 0 nhưng phải cùng biến

vd: 3xy, xy, \(\dfrac{-5}{3}\)xy, -5xy

Đơn thức thu gọn là đơn thức không còn hệ số hay biến giống nhau

vd:

Chưa thu gọn:

3xy . 6x

Tiến hành thu gọn:

3xy . 6x

=(3.6)(x.x).y

= 18x\(^2\)y

Vậy 18x\(^2\)y là đơn thức đã thu gọn

Còn lại bạn tự lấy vd nha!

Bài 2:

1)

Rút gọn:

\(\dfrac{-12}{15}=\dfrac{-4}{5}\)

\(\dfrac{-15}{20}=\dfrac{-3}{4}\)

\(\dfrac{24}{-32}=\dfrac{-3}{4}\)

\(\dfrac{-20}{28}=\dfrac{-5}{7}\)

\(\dfrac{-27}{36}=\dfrac{-3}{4}\)

Phân số biểu diễn số hữu tỉ \(\dfrac{-3}{4}\) là: \(\dfrac{-15}{20}\) ;\(\dfrac{24}{-32}\) ;\(\dfrac{-27}{36}\)

2) \(\dfrac{3}{-4}=\dfrac{-3}{4}\)

Biểu diễn:

C1:

A=\(\left(6-\dfrac23+\dfrac12\right)-\left(5+\dfrac53-\dfrac32\right)-\left(3-\dfrac73+\dfrac52\right)\)

=\(\left(\dfrac{16}{3}+\dfrac12\right)-\left(\dfrac{20}{3}-\dfrac32\right)-\left(\dfrac23+\dfrac52\right)\)

=\(\dfrac{35}{6}-\dfrac{31}{6}-\dfrac{19}{6}\)

=\(\dfrac23-\dfrac{19}{6}\)

=\(-\dfrac52\)

C2:

A=\(\left(6-\dfrac23+\dfrac12\right)-\left(5+\dfrac53-\dfrac32\right)-\left(3-\dfrac73+\dfrac52\right)\)

=\(6-\dfrac23+\dfrac12-5-\dfrac53+\dfrac32-3+\dfrac73-\dfrac52\)

=\(\left(6-5-3\right)+\left(-\dfrac23-\dfrac53+\dfrac73\right)+\left(\dfrac12+\dfrac32-\dfrac52\right)\)

=\(-2+0-\dfrac12\)

=\(-2-\dfrac12\)

=\(-\dfrac52\)

\(x^5+2x^5\)

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

\(=3x^5\)

------------

Giải thích:

Hệ số cộng với hệ số, phần biến giữ nguyên

Bài 5:

1) \(4x^4-4x^2+1\)

\(=\left(2x^2\right)^2-2\cdot\left(2x^2\right)\cdot1+1^2\)

\(=\left(2x^2-1\right)^2\)

2) \(4x^2-12x+9\)

\(=\left(2x\right)^2-2\cdot\left(2x\right)\cdot3+3^2\)

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

3) \(36+x^2-12x\)

\(=x^2-12x+36\)

\(=x^2-2\cdot x\cdot6+6^2\)

\(=\left(x-6\right)^2\)

4) \(1-10x+25x^2\)

\(=\left(5x\right)^2-2\cdot\left(5x\right)\cdot1+1^2\)

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

5) \(x^4+81+18x^2\)

\(=\left(x^2\right)^2+2\cdot\left(x^2\right)\cdot9+9^2\)

\(=\left(x^2+9\right)^2\)

6) \(4x^2-20x+25\)

\(=\left(2x\right)^2-2\cdot\left(2x\right)\cdot5+5^2\)

\(=\left(2x-5\right)^2\)

7) \(x^2+4y^4-4xy^2\)

\(=x^2-4xy^2+4y^4\)

\(=x^2-2\cdot x\cdot\left(2y^2\right)+\left(2y^2\right)^2\)

\(=\left(x-2y^2\right)^2\)

8) \(x^2+10xy+25y^2\)

\(=x^2+2\cdot x\cdot\left(5y\right)+\left(5y\right)^2\)

\(=\left(x+5y\right)^2\)

9) \(9y^2-24xy+16x^2\)

\(=\left(3y\right)^2-2\cdot\left(3y\right)\cdot\left(4x\right)+\left(4x\right)^2\)

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

\(\boxed{\star19/08/2004}\)

Bài này là sở hữu cách (Poss Nouns)

Dạng sở hữu cách là có 's

1. grandmother's

2. sister's

3. cousin's

4. Nam's

5. An's

\(\boxed{\star19/08/2004}\)

a) A=\(\left(3^2\right)^2-\left(-2^3\right)^2-\left(-5^2\right)^2\)

\(=3^{2\cdot2}-\left(-8\right)^2-\left(-25\right)^2\)

\(=3^4-64-625\)

\(=81-64-625\)

\(=17-625\)

\(=-608\)

Vậy A=-608

\(\boxed{\star19/08/2004}\)

Bải này thì chia dạng thôi, mình thấy cx khá dễ :v

1.

(-) The girl doesn't often listen to pop music.

(?) Does the girl often listen to pop mucsic?

2.

(-) I am not from the capital of Viet Nam, Ha Noi.

(?) Are you from the capital of Viet Nam, Ha Noi?

3.

(+) My father keeps the greenhouse warm at night.

(?) Does your father keep the greenhouse warm at night?

4.

(+) Danny remembers to phone his father on Sundays

(-) Danny doesn't remember to phone his father on Sundays

5

(+) They do their homework after school.

(?) Do they do their homework after school?