223k views
4 votes
Find two numbers whose product is 80 and whose sum is 18

User Tyler Zika
by
8.7k points

1 Answer

3 votes

Let X & Y be the two integers

X+Y=18 Y = 18-X

XY = 80

We can substitute 18-X for Y in the equation XY = 80

X(18-X) = 80

Distributing

18X - X2 = 80

Subtract 80 from both sides so that the equation is equal to 0

-X2 + 18X - 80 = 0

Multiply (or divide by -1 so that the leading coefficient is positive, not negative)

X2 - 18X + 80 = 0

We can factor this quadratic

(X-10)(X-8) = 0

Setting each factor equal to 0 we can solve for X.

X-10 = 0 X-8 = 0

X = 10 X = 8

The two integers are 8 and 10.Answer:

Explanation:

User Grundoon
by
8.0k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories