Giải thích các bước giải:
b) (2x – 3)(2x + 3) – (x + 5)2 – (x – 1)(x + 2)
= 4x2 – 9 – (x + 5)2 – (x – 1) (x + 2)
= 4x2 – 9 – (x2 + 10x + 25 ) – (x – 1)(x + 2)
= 4x2 – 9 – (x2 + 10x + 25 ) – ( x2 + 2x – x – 2 )
= 4x2 – 9 – x2 – 10x -25 – ( x2 + 2x – x – 2 )
= 4x2 – 9 – x2 – 10x – 25 - ( x2 + x – 2 )
= 4x2 – 9 – x2 – 10x – 25 - x2 - x + 2
= 2x2 – 9 - 10x – 25 – x + 2
= 2x2 – 32 – 10x – x
= 2x2 – 32 – 11x
= 2x2 –11x – 32
CHÚC BẠN HỌC TỐT
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