Question

Two numbers multiply to be -7 and add to be -6. What are the numbers? Example; 2,3

Answer 1

Given:

Let the two numbers be x and y.

Two numbers multiply to be -7 and add to be -6.

This can be written in equation as,

$xy=-7$ and

$x+y=-6$

Value of the two numbers:

Let us determine the value of the two numbers using substitution method.

Substituting $y=-6-x$ in the equation $xy=-7$, we get;

$x(-6-x)=-7$

Simplifying, we get;

       $-6x-x^2=-7$

   $x^2+6x-7=0$

$(x+7)(x-1)=0$

$x=-7, 1$

Thus, the values of x are x = 1,-7

When x = 1 , the equation $x+y=-6$ becomes $y=-7$

When x = -7, the equation $x+y=-6$ becomes $y=1$

Therefore, the two numbers are 1 and -7