quadratic equation x2 -4x - 5 =0? show work?

Answer 1

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

The trick is in the factorization. You need numbers that have a sum of - 4 and a product of - 5. -5 and +1 are the solution, hence (x - 5)(x + 1).

If the factorization is beyond you, you can always use the quadratic formula, x = (-b +/- sqrt(b^2 - 4ac)) / 2a, where the original equation is rewritten as ax^2 + bx + c. In this case, you get x = (4 +/- sqrt(4^2 - 4*1*(-5))) / (2*1) = (4 +/- sqrt(16 + 20)) / 2 = (4 +/- sqrt(36)) / 2 = (4 +/- 6) / 2 = (-2 or 10) / 2 = -1 or 5, which matches the above.

Answer 2

x2 – 4x – 5 = 0 (x - 5) (x + a million) = 0 So x = +5 or x = -a million For the quadratice equation: a = a million, b = -4, c = -5 Sqrt b^2 - 4ac = sqrt (sixteen - (4 * a million * -5)) = sqrt (sixteen - (-20)) = sqrt (36) = +6 or -6 The quadratic equation is then: [- (-4) +/- 6 ]/ 2 = 2 +/- 3 = +5 or -a million

Answer 3

First step is to find two numbers that multiply to give -5 and add to give - 4.
These numbers are - 5 and 1
(x - 5).(x + 1) = 0
x - 5 = 0 or x + 1 = 0
x = 5 , x = - 1

Answer 4

x=5,x= -1

Answer 5

x^2 - 4x - 5 = 0

Factor

(x - 5)(x + 1) = 0

Set factors equal to 0 and solve

x - 5 = 0
x = 5

x + 1 = 0
x = -1

The solutions are 5 and -1

Answer 6

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

x is = to either -1 or 5