14:

a: Sxq=(2+1,5)*2*1,2=2,4*3,5=8,4m²

V=2*1,5*1,2=2*1,8=3,6m³

b: Bể chứa được tối đa là: 3,6*1000=3600 lít

a) \(\dfrac{\sqrt{15}+\sqrt{21}}{\sqrt{5}+\sqrt{7}}=\dfrac{\sqrt{3}.\sqrt{5}+\sqrt{3}.\sqrt{7}}{\sqrt{5}.\sqrt{7}}=\dfrac{\sqrt{3}\left(\sqrt{5}.\sqrt{7}\right)}{\sqrt{5}.\sqrt{7}}=\sqrt{3}\)

a) \(\dfrac{\sqrt{15}+\sqrt{21}}{\sqrt{5}+\sqrt{7}}=\dfrac{\sqrt{3}\left(\sqrt{5}+\sqrt{7}\right)}{\sqrt{5}+\sqrt{7}}=\sqrt{3}\)

b: =1/3-1/3+3/5-3/5+5/7-5/7+7/9-7/9+9/11-9/11-11/13+11/13+13/15

=13/15

`1/3 - 3/5 + 5/7 - 7/9 + 9/11 -11/13 + 13/15 +11/13 - 9/11 + 7/9 - 5/7+3/5-1/3`

`= (1/3-1/3) +(-3/5 + 3/5) +(5/7-5/7)+(-7/9+7/9)+(9/11-9/11)+(-11/13+11/13)+13/15`

`=0 + 0 +0+0+0+0+13/15`

`=13/15`

b]

= [ 1/3 - 1/3 ] + [ 3/5 - 3/5 ] + [ 5/7 - 5/7 ] + [ 7/9 - 7/9 ] + [ 9/11 - 9/11 ] + [ 11/13- 11/13 ] + 13/15

= 0 + 0 + 0 + 0 + 0 + 0 + 13/15

= 13/15

\(b,=\left(x-4\right)^2\\ c,=x^2-25\\ d,=\left(x+4\right)^3\\ e,=\left(x-2\right)^3\\ f,=x^3+8\\ g,=x^3-27\\ i,=\left(x-1\right)\left(x+1\right)\\ l,=\left(2x-3\right)\left(2x+3\right)\\ m,=\left(4x-1\right)^2\\ p,=\left(x+3\right)\left(x^2-3x+9\right)\)

1 which

2 who 

3 0

4 whom

5 which

6 whose

7 that

8 which

Chọn A

3:

Bước 1: Chọn ô

Bước 2: Nhập dấu '='

Bước 3: Gõ công thức

Bước 4: Nhấn enter