Question

rút gọn bt sau: (2x-3)²-(2x+3)²

Answer 1

`@` `\text {Ans}`

`\downarrow`

`(2x - 3)^2 - (2x + 3)^2`

`= 4x^2 - 12x + 9 - (4x^2 + 12x + 9)`

`= 4x^2 - 12x + 9 - 4x^2 - 12x - 9`

`= (4x^2 - 4x^2) + (-12x - 12x) + (9-9)`

`= -24x`

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`@` CT: 

`(A + B)^2 = A^2 + 2AB + B^2`

`(A - B)^2 = A^2 - 2AB + B^2`

Answer 2

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

\(=\left[\left(2x-3\right)+\left(2x+3\right)\right]\left[\left(2x-3\right)-\left(2x+3\right)\right]\)

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

\(=4x\cdot-6\)

\(=-24x\)