Question

[Oh Sehun]

Bài 1 :  Phân tích đa thức thành nhân tử :

a)      X^2 – 5x +6        b ) 3x^2 + 9x – 30        c) x^2 – 3x + 2

d)X^2 – 9x + 18         e) x^2 -6x + 8               f) x^2 -5x -14

g) x^2 + 6x +5            h) x^2 – 7x +12            i) x^2 – 7x+ 10

Bài 2 :

a)      3x^2 – 5x  2             

b)      2x^2 + x -6

c)       7x^2 + 50x +7

d)      12x^2 +7 – 12

e)      15x^2 + 7x-2

f)       A^2 -5a – 14

g)      2m^2 + 10m + 8

h)      4p^2 – 36p + 56

i)        2x^2 + 5x + 2

Answer 1

[Edogawa Conan]

Bài 1: a) x² - 5x + 6 = x² - 2x - 3x + 6 = x(x - 2) - 3(x - 2) = (x - 3)(x - 2)

b) 3x² + 9x - 30 = 3x² + 15x - 6x - 30 = 3x(x + 5) - 6(x + 5) = (3x - 6)(x + 5) = 2(x - 2)(x + 5)

c) x² - 3x + 2 = x² - 2x - x + 2  = x(x - 2) - (x - 2) = (x - 1)(x - 2)

d) x² - 9x + 18 = x² - 3x - 6x + 18 = x(x - 3) - 6(x - 3) = (x - 6)(x - 3)

e) x² - 6x + 8 = x² - 2x - 4x + 8 = x(x - 2) - 4(x - 2) = (x - 4)(x - 2)

f) x² - 5x - 14 = x² - 7x + 2x - 14 = x(x - 7) + 2(x - 7) = (x + 2)(x - 7)

g) x² + 6x + 5 = x² + 5x + x + 5 = x(x + 5) + (x + 5) = (x + 1)(x + 5)

h) x² - 7x + 12 = x² - 3x - 4x + 12 = x(x - 3) -  4(x - 3) = (x - 4)(x - 3)

i) x² - 7x + 10 = x² - 2x - 5x + 10 = x(x - 2) - 5(x - 2) = (x - 5)(x - 2)

Answer 2

[zZz Cool Kid_new zZz]

Oh Sehun:Ít một thôi bạn ơi!Làm xong đống này chắc đến tuổi già mất:(

a

\(x^2-5x+6\)

\(=\left(x^2-3x\right)-\left(2x-6\right)\)

\(=\left(x-3\right)\left(x-2\right)\)

b

\(3x^2+9x-30\)

\(=x^2+3x-10\)

\(=\left(x^2-2x\right)+\left(5x-10\right)\)

\(=\left(x-2\right)\left(x+5\right)\)

c

\(x^2-3x+2\)

\(=\left(x^2-x\right)-\left(2x-2\right)\)

\(=\left(x-1\right)\left(x-2\right)\)

d

\(x^2-9x+18\)

\(=\left(x^2-3x\right)-\left(6x-18\right)\)

\(=\left(x-3\right)\left(x-6\right)\)

e

\(x^2-6x+8\)

\(=\left(x^2-2x\right)-\left(4x-8\right)\)

\(=\left(x-2\right)\left(x-4\right)\)

f

\(x^2-5x-14\)

\(=\left(x^2+2x\right)-\left(7x+14\right)\)

\(=\left(x+2\right)\left(x-7\right)\)

g

\(x^2+6x+5\)

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

\(=\left(x+1\right)\left(x+5\right)\)

h

\(x^2-7x+12\)

\(=\left(x^2-3x\right)-\left(4x-12\right)\)

\(=\left(x-3\right)\left(x-4\right)\)

i

\(x^2-7x+10\)

\(=\left(x^2-2x\right)-\left(5x-10\right)\)

\(=\left(x-2\right)\left(x-5\right)\)

P/S:Cho e xin phép tách câu ạ.