Solve the quadratic:
x2+x-42 = 0
a = 1, b = 1, c = -42
x = | -b ± √b2 - 4ac |
2a |
-b = -(1)
-b = -1
Δ = b2 - 4ac:
Δ = 12 - 4 x 1 x -42
Δ = 1 - -168
Δ = 169 <--- Discriminant
Since Δ > 0, we expect two real roots.
√Δ = √(169)
√Δ = 13
Numerator 1 = -b + √Δ
Numerator 1 = -1 + 13
Numerator 1 = 12
Numerator 2 = -b - √Δ
Numerator 2 = -1 - 13
Numerator 2 = -14
Denominator = 2 * a
Denominator = 2 * 1
Denominator = 2
Solution 1 = | Numerator 1 |
Denominator |
Solution 1 = 6
Solution 2 = | Numerator 2 |
Denominator |
Solution 2 = -7
(Solution 1, Solution 2) = (6, -7)
(6)2 + 1(6) - 42 ? 0
(36) + 642 ? 0
36 + 642 ? 0
0 = 0
(-7)2 + 1(-7) - 42 ? 0
(49) - 742 ? 0
49 - 742 ? 0
0 = 0