# Algebra.

posted by .

Help?
-Solve Polynomial Equations By factoring.

1. x^6-25x^4=0

2. y^3-3y^2=16y-48

3. x^3+2x^2-9x-18=0

4. x^3+x^2-4x-4=0

5. x^3-7x^2=-5x-30

6. a^4+2a^3+a^2=0

7. 3n^4-4n^2=-1

8. 8x^5+10x^4=4x^3+5x^2

9. 2n^4-9n^2+4=0

10. 8y^4 / y^2 - 4y^2 / y^2 =0

• Algebra. -

1. x^4(x^2 - 25) = 0
x^4(x+5)(x-5) = 0
x=0 or x=-5 or x=5

2. x^3 - 3y^2 - 16y + 48=0
use grouping
y^2(y-3) - 16(y - 3) = 0
(y-3)(y^2 - 16) = 0
(y-3)(y+4)(y-4) = 0
y = 3 or y = -4 or y = 4

3, 4 done the same way

5. x^3 - 7x^2 + 5x + 30 = 0
--- now simple or easy solution, are you you typed it correctly?

6. take out common factor of a^2, then it becomes easy

7 .
3x^4 - 4n^2 + 1 = 0
let n^2 = x, we get
3x^2 - 4x + 1 = 0
(3x - 1)(x - 1) = 0
x = 1/3 or x = 1
then n^2 = 1/3 or n^2 = 1
n = 1/±√3 or n = ± 1

8. move everbody to the left, then factor

9. similar to #7

10 8y^4 / y^2 - 4y^2 / y^2 =0
8y^2 - 4 = 0
divide by 4
2y^2 - 1 = 0
y^2 = 1/2
y = ± 1/√2

• typo - Algebra. -

#5 should say:

--- not a simple or easy solution, are you you typed it correctly?

• Algebra. -

Sorry No Didn't .
It should have been -35

• Algebra. -

Can You explain how to do 3?
i know it's like 2, but then if i factor everything out there's nothing left to make my two equations right?!