Question

bài 1, làm tính nhân :

a, xy(5x³-3xy²-\(\frac{1}{2}\))

b, (\(\frac{1}{3}x+1\))(3x-2)

c, (x-3)(x+3)-(2x-5)

bài 2,phân tích đa thức thành nhân tử :

a, 5x-10y

b, a²+4a-b²+4b

c, 2xy-x²-y²+25

d, 3x²-8x+4

e,. 6x²-24

f, 3x(x-5)-x+5

g, x²+12x+35

a,

Answer 1

2/

a, 5x - 10y = 5(x - 2y)

b, a² + 4a - b² + 4b

= (a² - b²) + (4a + 4b)

= (a - b)(a + b) + 4(a + b)

= (a + b)(a - b + 4)

c, 2xy - x² - y² + 25

= 25 - (x² - 2xy + y²)

= 5² - (x - y)²

= (5 - x + y)(5 + x - y)

d, 3x² - 8x + 4

= 3x² - 6x - 2x + 4

= 3x(x - 2) - 2(x - 2)

= (x - 2)(3x - 2)

e, 6x² - 24

= 6(x² - 4)

= 6(x - 2)(x + 2)

Answer 2

f) \(3x.\left(x-5\right)-x+5\)

\(=3x.\left(x-5\right)-\left(x-5\right)\)

\(=\left(x-5\right).\left(3x-1\right)\)

g) \(x^2+12x+35\)

\(=x^2+5x+7x+35\)

\(=\left(x^2+5x\right)+\left(7x+35\right)\)

\(=x.\left(x+5\right)+7.\left(x+5\right)\)

\(=\left(x+5\right).\left(x+7\right)\)

Chúc bạn học tốt!