What two numbers add up to make 2 and multiply to -4?

Answer 1

-2

Answer 2

Let one of the numbers be x then other number be 2-x.

According to question:

x(2-x) = -4

2x - x2 = -4

x2 - 2x - 4 = 0 which is a quadratic equation.

Standard form is ax2 + bx + c = 0.

Solutions of a quadratic equation can be found as:

x = [-b ± (b2 - 4ac)1/2]/2a

On comparing with standard form we can see clearly that:

a = 1, b = -2 and c = -4.

Putting the values of a,b and c in the above formula, we get:

x = [-(-2) ± ((-2)2 - 4(1)(-4))1/2]/2 = [2 ± (20)1/2]/2 = 1 ± 51/2.

So, the two numbers are (1 + 51/2) and (1 - 51/2).