F.2Maths!!!!!!!!!!!40p!!!!!!

6.(a)
24a²b + 15b + 12b² + 30a²
= (24a²b + 12b²) + (30a² + 15b)
= 12b(2a² + b) + 15(a² + b)
= (12b + 15)(2a² + b)
= 3(4b + 5)(2a² + b) ...... (answer)

6.(b)
20p³ - 6q³ + 15p²q² - 8pq
= (20p³ - 8pq) + (15p²q² - 6q³)
= 4p(5p² - 2q) + 3q²(5p² - 2q)
= (4p + 3q²)(5p² - 2q) ...... (answer)

6.(c)
15m³n² - 20 + 10n² - 30m³
= (15m³n² - 30m³) + (10n² - 20)
= 15m³(n² - 2) + 10(n² - 2)
= (15n³ + 10)(n² - 2)
= 5(3n³ + 2)(n² - 2) ...... (answer)

6.(d)
20x³y - 18y^4 - 15xy³ + 24x²y²
= (20x³y - 15xy³) + (24x²y² - 18y^4)
= 5xy(4x² - 3y²) + 6y²(4x² - 3y²)
= (5xy + 6y²)(4x² - 3y²)
= y(5x + 6y)(4x² - 3y²) ...... (answer)


7.
2a²b² + 2abc - 12c²
= 2a²b² + 6abc - 4abc - 12c²
= (2a²b² + 6abc) + (-4abc - 12c²)
= 2ab(ab + 3c) - 4c(ab + 3c)
= (2ab - 4c)(ab + 3c) ...... (answer)


8.
x^5 - x³ - 6x
= x^5 - 3x³ + 2x³ - 6x
= (x^5 - 3x³) + (2x³ - 6x)
= x³(x² - 3) + 2x(x² - 3)
= (x³ + 2x)(x² - 3)
= x(x² + 2)(x² - 3) ...... (answer)

2009-10-02 01:05:31 補充：
7.7.
2a²b² + 2abc - 12c²
= 2a²b² + 6abc - 4abc - 12c²
= (2a²b² + 6abc) + (-4abc - 12c²)
= 2ab(ab + 3c) - 4c(ab + 3c)
= (2ab - 4c)(ab + 3c)
= 2(ab - 2c)(ab + 3c) ...... (answer)