Question

bài 9 ; thực hiện phép tính

1) 20x⁵ : 5x              2) 12x⁴ : 6x³            3) 35x⁷ : 5x³             4) 21x¹² : 5x²

5) 14x⁴ : 3x²             6) 15x⁵ : 7x³            7) 22x⁷ : 4x              8) 18x⁶ : 2x⁶

9) -30x⁶ : 3/4x⁵         10) 9x⁹ : ( 3/10x³)      11) -6x⁸ : ( 3/7x⁴)     

12) 4x²⁰ : (-2/5x ¹⁰)

Answer 1

`5, 14x^4 : 3x^2 = (14 : 3) . (x^4 : x^2) = 14/3x^2`

`6, 15x^5 : 7x^3 = (15 : 7) . (x^5 : x^3) = 15/7x^2`

`7, 22x^7 : 4x = (22 : 4) . (x^7 : x)= 11/2x^6`

`8, 18x^6 : 2x^6 = (18 : 2) . (x^6 : x^6)= 9`

Answer 2

`1, 20x^5 : 5x = (20 : 5) . (x^5 : x) = 4x^4`

`2, 12x^4 : 6x^3 = (12 : 6).(x^4 : x^3) = 2x`

`3, 35x^7 : 5x^3 = (35 : 5) . (x^7 : x^3) = 7x^4`

`4, 21x^12 : 5x^2 = (21 :5). (x^12 : x^2) = 21/5x^10`

Answer 3

1: \(\dfrac{20x^5}{5x}=\dfrac{20}{5}\cdot\dfrac{x^5}{x}=4x^4\)

2: \(12x^4:6x^3=\dfrac{12}{6}\cdot\dfrac{x^4}{x^3}=2x\)

3: \(35x^7:5x^3=\left(35:5\right)\cdot x^7:x^3=7x^4\)

4: \(21x^{12}:5x^2=\left(21:5\right)\cdot x^{12}:x^2=\dfrac{21}{5}x^{10}\)

5: \(\dfrac{14x^4}{3x^2}=\dfrac{14}{3}\cdot\dfrac{x^4}{x^2}=\dfrac{14}{3}x^2\)

6: \(\dfrac{15x^5}{7x^3}=\left(\dfrac{15}{7}\right)\cdot\dfrac{x^5}{x^3}=\dfrac{15}{7}x^2\)

7: \(22x^7:4x=\left(\dfrac{22}{4}\right)\cdot\dfrac{x^7}{x}=\dfrac{11}{2}x^6\)

8: \(18x^6:2x^6=18:2\cdot\dfrac{x^6}{x^6}=9\)

9: \(-30x^6:\dfrac{3}{4}x^5=\left(-30:\dfrac{3}{4}\right)\cdot\dfrac{x^6}{x^5}=-40x\)

10: \(9x^9:\left(\dfrac{3}{10}x^3\right)=\left(9:\dfrac{3}{10}\right)\cdot x^6=30x^6\)

11: \(-6x^8:\left(\dfrac{3}{7}x^4\right)=\left(-6:\dfrac{3}{7}\right)\cdot\dfrac{x^8}{x^4}=-14x^4\)

12: \(4x^{20}:\left(-\dfrac{2}{5}x^{10}\right)=\left(4:\dfrac{-2}{5}\right)\cdot\left(\dfrac{x^{20}}{x^{10}}\right)=-10x^{10}\)

Answer 4

`9. -30x^6 : 3/4x^5 = (-30 : 3/4) . (x^6 : x^5) = -40x`

`10, 9x^9 : (3/10x^3) = (9 : 3/10) . (x^9 : x^3) = 30x^6`

`11, -6x^8  : (3/7x^4) =(-6 : 3/7).(x^8:x^4) = -14x^4`

`12, 4x^20 : (-2/5x^10) = (4 : (-2)/5) . (x^20 : x^10) = -10x^10`