Question

câu 2 ạ

Answer 1

`a, 99^3 + 3 . 99^2 + 3 . 99 + 1`

`= 99^3 + 3 . 99^2 . 1 + 3 . 99 . 1^2 + 1^3`

`= (99 + 1)^3`

`= 100^3`

`= 1000000`

 

Answer 2

a: \(99^3+3\cdot99^2+3\cdot99+1\)

\(=99^3+3\cdot99^2\cdot1+3\cdot99\cdot1^2+1^3\)

\(=\left(99+1\right)^3=100^3=1000000\)

b: \(x^4-2x^2y-x^2+y^2+y\)

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

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

\(=6^2-6=36-6=30\)

Answer 3

`b,` Ta có:

`x^2- y = 6`

`=> y = x^2 - 6`

Thay `y = x^2 - 6,` ta có:

`x^4 - 2x^2(x^2 - 6) - x^2 + (x^2 - 6)^2 + (x^2 - 6)`

`= x^4 - 2x^4 + 12x^2 - x^2 + (x^4 - 12x^2 + 36) + x^2 - 6`

`= x^4 - 2x^4 + 12x^2 - x^2 + x^4 - 12x^2 + 36 + x^2 - 6`

`= (x^4 - 2x^4 + x^4) + (12x^2 - x^2 - 12x^2 + x^2) + 36 - 6`

`= 30`