1) 5 + (-4) = 1

2) (-8) + 2 = -6

3) 8 + (-2) = 6

4) 11 + (-3) = 8

5) (-11) + 2 = -9

6) (-7) + 3 = -4

7) (-5) + 5 = 0

8) 11 + (-12) = -1

9) (-18) + 20 = 2

10) (15) + (-12) = 3

11) (-17) + 17 = 0

12) 16 + (-2) = 14

13) (30) + (-14) = 16

14) (-19) + 20 = 1

15) (-18) + 15 = -3

16) (10) + (-6) = 4

17) (-28) + 14 = -14

18) 15 + (-30) = -15

19) (15) + (-4) = 11

20) (-21) + 11 = -10

21) 8 + (-22) = -14

22) (-15) + 4 = -11

23) (-3) + 2 = -1

24) 17 + (-14) = 3

25) 17 + (-14) = 3

thế này đọc đc mới đỉnh

`@` `\text {Ans}`

`\downarrow`

`(x^2 + 2)^2`

`= x^4 + 4x^2 + 4`

____

`@` Áp dụng: `(A+B)^2 = A^2 + 2AB + B^2.`

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

\(=\left(x^2\right)^2+2\cdot x^2\cdot2+2^2\)

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

\(50+2\left(7-2\right)^2\\ =50+2.5^2\\ =50+2.25\\ =50+50\\ =100.\)

\(50+2(7-2)^2\\=50+2\cdot 5^2\\=50+2\cdot25\\=50+50\\=100\)

\(=\dfrac{3}{2\left(x+3\right)}+\dfrac{6-x}{2x\left(x+3\right)}=\dfrac{3x+6-x}{2x\left(x+3\right)}=\dfrac{2x+6}{2x\left(x+6\right)}=\dfrac{2\left(x+3\right)}{2x\left(x+3\right)}=\dfrac{1}{x}\)

\(=\dfrac{3x+6-x}{2x\left(x+3\right)}=\dfrac{2x+6}{2x\left(x+3\right)}=\dfrac{1}{x}\)

\(S=-\left(1+2+...+2^{2009}+2^{2010}\right)\)

\(-2S=2\left(1+2+...+2^{2009}+2^{2010}\right)\)

\(\Rightarrow-2S+S=-S=2+2^2+...+2^{2010}+2^{2011}-1-2-...-2^{2009}-2^{2010}\)

\(-S=2^{2011}-1\Rightarrow S=1-2^{2011}\)

S=2²⁰¹⁰ - 2²⁰⁰⁹ - 2^{2008 -...-2-1}

=>2S=2 x 2²⁰¹⁰ - 2 x 2²⁰⁰⁹ - 2 x 2²⁰⁰⁸ -...-2 x 2 -2 x 1

2S=2²⁰¹¹ - 2²⁰¹⁰ - 2²⁰⁰⁹ - ... - 2² -2

=>S=1-2²⁰¹¹

Ta có:  ( - 2 ) 5 : ( - 2 ) 3 = ( - 2 ) 5 - 3 = ( - 2 ) 2 = 4 .

\(100x^2-49y^2=\left(10x-7y\right)\left(10x+7y\right)\)

Ta có: \(\left(x+3\right)^2+\left(x-3\right)^2+2\left(x^2-9\right)\)

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

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