Q= 2x²–3x+1

a)thể tích của hình hộp chữ nhật đã cho là:

x(x–1) (x+1)x³

b)tại x=4,thể tích của hình hộp chữ nhật là:

4³–4=60(cm³)

5x(4x²–2x+1)–2x(10x²–5x+2)=–36

5x.4x²+5x.(–2x)+5x.1+(–2x).10x²+(–2x).(–5x)+(–2x).2=–36

20x³+(–10x²)+5x(–20x³)+10x²+(–4x)=–36

(20x³–20x³)+(–10x²+10x²)+(5x–4x)=–36

x=–36

Vậy x=–36

5x(4x²–2x+1)–2x(10x²–5x+2)=–36

5x.4x²+5x.(–2x)+5x.1+(–2x).10x²+(–2x).(–5x)+(–2x).2=–36

20x³+(–10x²)+5x(–20x³)+10x²+(–4x)=–36

(20x³–20x³)+(–10x²+10x²)+(5x–4x)=–36

x=–36

Vậy x=–36

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4

b)R(x)=P(x)–Q(x)

=(x⁴–5x³+4x–5)–(–x⁴+3x²+2x+1)

=x⁴–5x³+4x–5x⁴–3x²–2x–1

=(x⁴+x⁴)–5x³–3x²+(4x–2x)+(–1–5)

=2x⁴–5x³–3x²–2x+6

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4

a)P (x) + Q (x)

= (x⁴ – 5x³ + 4x –5 )+(–x⁴ + 3x²+2x+1)

=x⁴–5x³+4x–5–x⁴+3x²+2x+1

=( x⁴–x⁴)–5x³+3x²+(4x+2x)+(1–5)

=–5x³+3x²+6x–4