Question

1. (x+3 )² - (x-3)² = 6x+18

2. ( x+1)³ - x ( x+1)²= 5x (2-x )-11 (x+2)

Answer 1

1. \(\Leftrightarrow\)\(\left(x^2+6x+9\right)-\left(x^2-6x+9\right)=6x+18\)

\(\Leftrightarrow\)\(x^2+6x+9-x^2+6x-9=6x+18\)

\(\Leftrightarrow\)12x-6x=18

\(\Leftrightarrow\)6x=18

\(\Leftrightarrow\)x=3

S=\(\left\{3\right\}\)

2.

Answer 2

câu 2 lần sau làm

Answer 3

2: =>x^3+3x^2+3x+1-x^3-2x^2-x=10x-5x^2-11x-22

=>x^2+2x+1=-5x^2-x-22

=>6x^2+3x+23=0

Δ=3^2-4*6*23

=9-24*23<0

=>PTVN