203k views
5 votes
Find two numbers whose product 9.8 =72 and whose sum is -38

User Enriquein
by
7.2k points

1 Answer

7 votes

Answer:Let's call the two numbers x and y. We know that:

xy = 72

x + y = -38

We can use the first equation to solve for one of the variables in terms of the other:

x = 72/y

Then, we can substitute this expression into the second equation:

72/y + y = -38

y^2 + 72 = 38y

y^2 - 38y + 72 = 0

This is a quadratic equation that can be solved using the quadratic formula:

y = (-b ± √(b^2 - 4ac)) / 2a

where a = 1, b = -38, c = 72.

Plugging in these values, we get:

y = (38 ± √(38^2 - 4(1)(72))) / 2(1)

y = (38 ± √(1444)) / 2

y = (38 ± 38) / 2

So, we have two solutions for y:

y = 38 / 2 = 19

y = -38 / 2 = -19

With either of these values for y, we can use the first equation to solve for x:

x = 72/y = 72/19 = 3.8

or

x = 72/-19 = -3.8

So, the two numbers whose product is 72 and whose sum is -38 are x = 3.8 and y = 19, or x = -3.8 and y = -19.

Explanation:

Let's call the two numbers x and y. We know that:

xy = 72

x + y = -38

We can use the first equation to solve for one of the variables in terms of the other:

x = 72/y

Then, we can substitute this expression into the second equation:

72/y + y = -38

y^2 + 72 = 38y

y^2 - 38y + 72 = 0

This is a quadratic equation that can be solved using the quadratic formula:

y = (-b ± √(b^2 - 4ac)) / 2a

where a = 1, b = -38, c = 72.

Plugging in these values, we get:

y = (38 ± √(38^2 - 4(1)(72))) / 2(1)

y = (38 ± √(1444)) / 2

y = (38 ± 38) / 2

So, we have two solutions for y:

y = 38 / 2 = 19

y = -38 / 2 = -19

With either of these values for y, we can use the first equation to solve for x:

x = 72/y = 72/19 = 3.8

or

x = 72/-19 = -3.8

So, the two numbers whose product is 72 and whose sum is -38 are x = 3.8 and y = 19, or x = -3.8 and y = -19.

User Jack Kelly
by
7.1k points