Question

019. If x + y = 9, x - y = -5 then 4 xy is
a. 65
b. 45
c. 56
c. 35

Answer 1

Step-by-step explanation:

I think the answer is 65 I think this is the correct answer

Answer 2

Answer:

use the identity

(x-y)² = (x+y)²-4xy

Step-by-step explanation:

(-5)² = 9² - 4xy

4xy = 81-25

4xy = 56

hope this helps

or u can do

subtract the both equation

x+y = 9

- x-y = -5

_______

2y = 14

y = 7

now

x+7= 9

x= 2

now

4xy

4*7*2

56