- #1
mathdad
- 1,283
- 1
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?
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?