急! 急 ! F4 Quadratic Equations.

22a.
△ = 0
(k+3)^2 - 4(-1)k = 0
k^2 + 6k + 9 + 4k = 0
k^2 + 10k + 9 = 0
(k+9)(k+1) = 0
k = -9 or -1
b.
When k = -9, -9x^2 - 6x - 1 = 0
(3x+1)^2 = 0
x = -1/3
When k = -1, -x^2 + 2x - 1 = 0
(x-1)^2 = 0
x = 1
23a.
△ = 0
m^2 - 4(m-2)(2) = 0
m^2 - 8m + 16 = 0
(m-4)^2 = 0
m = 4
b.
2x^2 + 4x + 2 = 0
x^2 + 2x + 1 = 0
(x+1)^2 = 0
x = -1
24a.
△ < 0
6^2 - 4(-1)(a-9) < 0
36 + 4a - 36 < 0
a < 0
b.
0, since the graph shows no intersection points of y and x-axis
25a.
△ >= 0
24^2 - 4(9)(p-1) >= 0
576 - 36p + 36 >= 0
p <= 17
b.
When p is max, p = 17,
2x^2 + 15x + 28 =0
(x+4)(2x+7) = 0
x = -4 or -7/2

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