Question

81-(9-x^2)^2

viết biểu thức sau dưới dạng tích

Answer 1

Ta có: \(81+\left(9-x^2\right)^2\)

Tương tự: \(81+-x^4+18x^2+-81\)

\(=\left(-x^4\right)+\left(18x^2\right)+\left(81+-81\right)\)

\(=-x^4+18x^2\)

Answer 2

\(81-\left(9-x^2\right)^2\)

\(=\)\(9^2-\left(3^2-x^2\right)^2\)

\(=\)\(9^2-\left(9-x^2\right)^2\)

\(=\)\(\left(9-9+x\right)\left(9+9-x\right)\)

\(=\)\(x\left(18-x\right)\)

Chúc bạn học tốt ~ 

Answer 3

81-(9-x^2)^2

=9^2-(3^2-x^2)^2

=9^2-(9- x^2)^2

=(9-9+x).(9+9-x)

​=x.(18-x)