Question

If x-y=1 and xy= 56 then find the value of x+y​

Answer 1

15

Explanation:

First, find the factors of 56

56: 1,2,4,7,8,14,28,56.

Since the problem says, x-y=1, that just proves that the two numbers(x and y) needs to be consecutive. If you apply that thought to the factors of 56, you will discover that the only consecutive pairs of factors are 7 and 8.

Next, you have to check.

8-7=1.

8 times 7 = 56

So, 8+7 should be 15. That is your answer :)

Answer 2

x + y = ±15

Explanation:

Step 1: Write out systems of equations

x - y = 1

xy = 56

Step 2: Rearrange 1st equation

x = y + 1

Step 3: Substitution

(y + 1)y = 56

Step 4: Distribute

y² + y = 56

Step 5: Solve for y

y² + y - 56 = 0

(y - 7)(y + 8) = 0

y = -8, 7

Step 6: Plug in y to find x

x - 7 = 1

x = 8

x - (-8) = 1

x + 8 = 1

x = -7

Step 7: Find answer

x + y = ?

8 + 7 = 15

-7 + -8 = -15

So both 15 and -15 could be the answer.