Question

chứng minh đẳng thức sau :

a) x(x+1)(x+2)=x³+3x²+2x

tìm x biết :

b) (3x - 2)(4x - 5) - (2x -  1)(6x+2) = 0 

Answer 1

\(a)\)\(VP=x^3+3x^2+2x\)

\(VP=x\left(x^2+3x+2\right)\)

\(VP=x\left[\left(x^2+x\right)+\left(2x+2\right)\right]\)

\(VP=x\left[x\left(x+1\right)+2\left(x+1\right)\right]\)

\(VP=x\left(x+1\right)\left(x+2\right)\) ( đpcm ) 

Chúc bạn học tốt ~ 

Answer 2

a) x(x+1)(x+2)=(x²+x)(x+2)=x³+2x²+x²+2x=x³+3x²+3x

b)

(3x - 2)(4x - 5) - (2x - 1)(6x + 1) = 0

12x2 - 15x - 8x + 10 - 12x2 - 2x + 6x + 1 = 0

- 19x = - 11

x = 11/19

Answer 3

\(\left(3x-2\right)\left(4x-5\right)-\left(2x-1\right)\left(6x+2\right)=0\)

\(12x^2-23x+10-12x^2+2x+2=0\)

\(-21x=-12\)

\(x=\frac{-12}{-21}=\frac{4}{7}\)

Vậy \(x=\frac{4}{7}\)

Tham khảo nhé~

Answer 4

a) Phùng Minh Quân làm đúng rồi

b) \(\left(3x-2\right)\left(4x-5\right)-\left(2x-1\right)\left(6x+2\right)=0\)

\(12x^2-23x+10-12x^2+2x+2=0\)

\(-21x+12=0\)

\(3\left(4-7x\right)=0\)

\(\Leftrightarrow4-7x=0\)

\(\Leftrightarrow x=\frac{4}{7}\)

Vậy,.....

Answer 5

a,\(x\left(x^2+3x+2\right)=x\left(x^2+x+2x+2\right)=x\left(x+1\right)\left(2x+1\right)\)  \(2\))

b,k biết