Yes, that is correct! Great job factoring the expression.

[mathdad]

Factor the expression.

t^4 - 9t^2 + 20

My Solution

(t^2)^2 - 9t^2 + 20

Let u = t^2

u^2 - 9u + 20

(u - 5)(u - 4)

I can back-substitute for u.

(t^2 - 5)(t^2 - 4)

I see that t^2 - 4 is the difference of two perfect squares.

Answer: (t^2 - 5)(t - 2)(t + 2)

Correct?

 

[MarkFL]

Looks good. (Yes)

 

[mathdad]

Looks good. (Yes)

Very good. Good night. More factoring questions on Friday.