Problems with these algebra questions

Well I decided to test myself with some questions involving Algebra and I can not for the life of me figure out these problems. I would like to know if you an solve them for me, and I will be truly grateful, and also show the work, please? I also want to know how to solve them, so I can do it on my own.
It tells me to: Solve each equation by factoring.
9.) 21n^2 + 6 = 23n 10.) 7n^2 = -21 + 52n

11.) 40x^2 = -144 + 246x 12.) 21n^2 - 182n = -336

Also if you can show work and help me on these, please? Solve each equation by taking square roots
1.) 2b^2 + 6 = 24 2.) 4b^2 + 2 = 102
3.) 3a^2 - 2 = 241 4.) 7p^2 - 5 = 247

21n^2 + 6 = 23n
21n^2 - 23n + 6 = 0
21n^2 - 14n - 9n + 6 = 0
7n(3n - 2) - 3(3n - 2) = 0
(7n - 3)(3n - 2) = 0
n = {3/7, 2/3}

7n^2 = -21 + 52n
7n^2 - 52n + 21 = 0
7n^2 - 49n - 3n + 21 = 0
7n(n - 7) - 3(n - 7) = 0
(7n - 3)(n - 7) = 0
n = {3/7, 7}

40x^2 = -144 + 246x
40x^2 - 246x + 144 = 0
20x^2 - 123x + 72 = 0
can't solve by factoring
equation is prime
x = (123 ± √9369) / 40

21n^2 - 182n = -336
21n^2 - 182n + 336 = 0
3n^2 - 26n + 48 = 0
(3n - 8)(n - 6) = 0
n = {8/3, 6}

2b^2 + 6 = 24
2b^2 = 18
b^2 = 9
b = ± √9
b = ± 3

4b^2 + 2 = 102
4b^2 = 100
b^2 = 25
b = ± √25
b = ± 5

3a^2 - 2 = 241
3a^2 = 243
a^2 = 81
a = ± √81
a = ± 9

7p^2 - 5 = 247
7p^2 = 252
p^2 = 36
p = ± √36
p = ± 6

@ other David, reduced in the line above. I didn't forget anything. You forgot that there are two answers for #'s 1,2,3 and 4

1.)
21n^2 + 6 = 23n
21n^2 -23n +6 = 0

n = [23 +/- sqrt(23^2 -4*21*6)] / 2*21

n = [23 +/- 5] / 42
n = 28/42, and n = 18/42

n = 2/3, and, n = 3/7 >=================< ANSWER

2.)
7n^2 = -21 + 52n
7n^2 -52n +21 = 0

n = [52 +/- sqrt(52^2 -4*7*21)] / 2*7

n = [52 +/- 46] / 14 = 98/14, and, n = 6/14

n = 7, and, n = 3/7 >=================< ANSWER

Similarly solve the others ...............

9) 21n^2 + 6 = 23n
21n^2 - 23n + 6 = 0
(3n - 2)(7n - 3) =0
n= 2/3 or 3/7

10) 7n^2 - 52n + 21=0
(n-7)(7n-3)=0
n=7 or 3/7



12) 21n^2 - 182n +336=0
7(x-6)(3x-8)=0
x= 6 or 8/3

1) 2b^2=18
b^2=9
b=3

2) 4b^2=100
b^2=25
b=5

3) 3a^2=243
a^2=81
a=9

4) 7p^2=252
p^2=36
p=6


@ David forgot the multiplier 7 infront of the p for q's 4