Question

tìm x

(x+3).(x\(^{ }\)\(^2\) - 3x + 9)-x(x-2).(x+2)=15

Answer 1

\(\Leftrightarrow x^3+27-x\left(x^2-4\right)=15\)

\(\Leftrightarrow4x+27=15\)

=>4x=-12

hay x=-3

Answer 2

(x+3).(x²-3x+9)-x(x-2).(x+2)=15

\(\Leftrightarrow\)(x³+3³)-x(x²-2²)=15

 \(\Leftrightarrow\)x³+3³-x³+2²x=15

 \(\Leftrightarrow\)27+4x=15

\(\Leftrightarrow\) 4x=15-27

\(\Leftrightarrow\) 4x= -12​​

\(\Leftrightarrow\)x=-12/4\(\Leftrightarrow\)x=-3thỉnh cao nhân chỉ điểm