:)

1.B dynamite
2.B disappear
3.B refreshment
4.C disappointed
5.C division
6.C disappointment
7.B congratulate
8.D inedible
9.C congratulation
10.A oceanic

--thodagbun--

1 A

3 C

4 C

5 A

6 B

10 A

1 If we continue polluting the air, the environment will be affected seriously

2 If we don't stop damaging birds' homes, there will be fewer birds left

3 If we continue polluting the water, there will be more disease in people and animals

4 If we keep polluting the land, the soil will not be safe enough for us to grow food in

5 If we use public transportation when we need, there will be less air pollution

12 Daniel signs up for a clean-up campaign so that he can join in it

13 People in my neighborhood clean the park up so that their children will have a nice place to play

14 Almost all the students in my school plant trees so that they can have much fresher air

9. A
10. D
5. A
6. B
7. D
8. B
 

9 A

10 D

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

n: \(=5\cdot x^m\cdot x^2+10x^2\)

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

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

\(=\left(x-2y\right)\left(5x+2x-4y\right)\)

=(x-2y)(7x-4y)

p: \(=7x\left(y-4\right)^2+\left(y-4\right)^3\)

\(=\left(y-4\right)^2\cdot\left(7x+y-4\right)\)

q: \(\left(4x-8\right)\left(x^2+6\right)-\left(4x-8\right)\left(x+7\right)+9\left(8-4x\right)\)

\(=\left(4x-8\right)\left(x^2+6-x-7\right)-9\left(4x-8\right)\)

\(=\left(4x-8\right)\left(x^2-x-10\right)\)

\(=4\left(x-2\right)\left(x^2-x-10\right)\)

m) \(x^{m+2}-x^m\)

\(=x^m\cdot x^2-x^m\)

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

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

\(=x^m\left(x-1\right)\left(x+1\right)\)

n) \(5x^{m+2}+10x^2\)

\(=5x^m\cdot x^2+10x^2\)

\(=5x^2\cdot x^m+10x^2\)

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

o) \(5x\left(x-2y\right)+2\left(2y-x\right)^2\)

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

\(=\left(x-2y\right)\left[5x+2\left(x-2y\right)\right]\)

\(=\left(x-2y\right)\left(5x+2x-4y\right)\)

\(=\left(x-2y\right)\left(7x-4y\right)\)

p) \(7x\left(y-4\right)^2-\left(4-y\right)^3\)

\(=7x\left(4-y\right)^2-\left(4-y\right)^3\)

\(=\left(4-y\right)^2\left[7x-\left(4-y\right)\right]\)

\(=\left(4-y\right)^2\left(7x-4+y\right)\)

q) \(\left(4x-8\right)\left(x^2+6\right)-\left(4x-8\right)\left(x+7\right)+9\left(8-4x\right)\)

\(=4\left(x-2\right)\left(x^2+6\right)-4\left(x-2\right)\left(x+7\right)-36\left(x-2\right)\)

\(=4\left(x-2\right)\left[\left(x^2+6\right)-\left(x+7\right)-9\right]\)

\(=4\left(x-2\right)\left(x^2+6-x-7-9\right)\)

\(=4\left(x-2\right)\left(x^2-x-10\right)\)

\(x:y:z=\dfrac{4}{7}:\dfrac{5}{8}:\dfrac{9}{10}=160:175:252\)

Giúp e vs e đg rất gấp ạ

\(4x^4+1\)

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

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

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

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

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

a) \(f\left(x\right)+g\left(x\right)-h\left(x\right)\)

\(=\left(2x^5-4^4x^4+3x^3-x^2+5x-1\right)+\left(-x^5+2x^4-3x^3-x^2-2x+7\right)-\left(x^5-2x^4-2x^2-x-3\right)\)

\(=2x^5-4x^4+3x^3-x^2+5x-1-x^5+2x^4-3x^3-x^2-2x+7-x^5+2x^4+2x^2+x+3\)\(=\left(2x^5-x^5-x^5\right)-\left(4x^4-2x^4-2x^4\right)+\left(3x^3-3x^3\right)-\left(x^2+x^2-2x^2\right)+\left(5x-2x+x\right)-\left(1-7-3\right)\)

\(=0-0+0-0+4x-9\)

\(=4x-9\)

`a,`

`f(x)+g(x)-h(x)=(2x^5-4x^4+3x^3-x^2+5x-1)+(-x^5+2x^4-3x^3-x^2-2x+7)-(x^5-2x^4-2x^2-x-3)`

`= 2x^5-4x^4+3x^3-x^2+5x-1+ -x^5+2x^4-3x^3-x^2-2x+7-x^5+2x^4+2x^2+x+3`

`= (2x^5-x^5-x^5)-(4x^4-2x^4-2x^4)+(3x^3-3x^3)-(x^2-2x^2)-(2x-x)+(-1+7+3)`

`= 0-0+0-(-x^2)-x+10 = x^2-x+9`

cho mình làm lại ;-;

`a,`

`f(x)+g(x)-h(x)=(2x^5-4x^4+3x^3-x^2+5x-1)+(-x^5+2x^4-3x^3-x^2-2x+7)-(x^5-2x^4-2x^2-x-3)`

`= 2x^5-4x^4+3x^3-x^2+5x-1+ -x^5+2x^4-3x^3-x^2-2x+7-x^5+2x^4+2x^2+x+3`

`= (2x^5-x^5-x^5)-(4x^4-2x^4-2x^4)+(3x^3-3x^3)-(x^2+x^2-2x^2)+(5x-2x+x)+(-1+7+3)`

`= 0-0+0-0+4x+9 = 4x+9 `