1. Làm tính nhân:
1
a. ( x
2 – 2x + 3 )(
2 x – 5 )
= x
2.
2 x – 2x .
2 x + 3.
2 x - x
2. 5
. + 2x . 5 – 3. 5
23
3
=
2 x - 15
2 x – 5x
2 + 10x – 15 =
2 x
3 – 6x
2 +
2 x
3 – x
2 +
b. ( x
3 – 2x
2 + x – 1)( 5 – x )
= x
3. 5 - 2x
2. 5 + x.5 - 1 . 5 – x
3. x +2x
2.x - x. x + 1. x
= 5x
3 – 10x
2 + 5x – 5 – x
4 + 2x
3 – x
2 + x
= - x
4 + 7x
3 – 11 x
2 + 6x – 5
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