N8

1)x^4 - x^2 = x^2(x^2-1)  x = 0 x = 1 x = -1

2) x^5 - 16 x^3 = x^3(x^2 - 4) x=0 x = 2 x= -2

3)9x^2+6x+1 = (3x+1)^2 x = -1/3

4) x^3 - 25x = x(x^2 - 25) x = 0 x = 5  x = -5

5) 25x^2 - 16 = (5x-4)*(5x+4) x = 4/5 x = -4/5

6)3(y+5)^2 y = -5

7) 0.7(1-3x)^2 x = 1/3

8)1/2(3-2x)^2=0 x = 3/2

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

10) 25y^2 - 4 = (5y-2)(5y+2) y = 2/5 y = -2/5

11) x^2 - 6x + 9 = (x-3)^2 x = 3

N7

1)(x-2)^2 = x^2 

x^2-4x+4 = x^2

4x = 4  x = 1

2)(c-7)^2 = c^2 - 7

c^2 - 14c + 49 = c^2 - 7

14c = 56

c = 4

3) x^2 - 9 -4x = x^2 - 2x + 1 - 5

2x = -5 x = -2.5

4) c^2 +9 = 6c

c^2 - 6c +9 =0

(c-3)^2 = 0 c=3

5)9x - 6(x-3)= 20(0.2x - 1.3)

9x - 6x + 18 = 4x - 26

x = 44