22.2k views
2 votes
An integer is 17 more than 4 times another. If the product of the two integers is -15, then find the integers.

User Svarog
by
7.6k points

1 Answer

6 votes

Let's use algebra to solve this problem.

Let x be one of the integers, and y be the other integer.

From the problem, we know that:

x = 4y + 17 (one integer is 17 more than 4 times the other)

xy = -15 (the product of the two integers is -15)

We can use substitution to solve for one of the variables. From the first equation, we can write:

y = (x - 17)/4

Substituting this expression for y into the second equation gives:

x(x - 17)/4 = -15

Multiplying both sides by 4 and expanding gives:

x^2 - 17x = -60

Rearranging gives:

x^2 - 17x + 60 = 0

This is a quadratic equation that can be factored as:

(x - 5)(x - 12) = 0

So the solutions are:

x = 5, y = (-12/4) = -3

x = 12, y = (-5/4) = -1.25

Since the problem states that the integers are both integers, the only valid solution is:

x = 5, y = -3

Therefore, the two integers are 5 and -3.

User Zenperttu
by
7.4k points