Question

if (x+y) =9, xy = 20 find (x-y)​

Answer 1

Answer:

solved below

Step-by-step explanation:

x+y=9

so x=9-y

xy=20

(9-y)y=20

9Y-y^2=20

y^2-9y+20=0

(y-5)(y-4)=0

y=5 or 4

if y=4 then x=5

then x-y=1

and then interchange x and y

Answer 2

Step-by-step explanation:

(x+y) =9

Therefore x = 9-y

xy= 20

Therefore

(9-y) (y) =20

9y -y^2 =20

9y-y^2-20 =0

- ( - 9y + y^2 + 20) = 0

Now transposing - to the = sign

It becomes -9y + y^2 + 20 = - 0

But since 0 has neither negative nor positive value

Therefore it becomes

-9y + y^2 + 20 = 0

Or

y^2 -9y + 20 = 0

Now Factorization by middle term breaking

y^2 - ( 5+ 4 ) y + 20 = 0

y^2 - 5y - 4y + 20 = 0

y(y-5) -4(y-5) = 0

(y-5)(y-4) = 0

Now ,

y can be either 5 or 4

Let's consider y to be 4

Therefore ,

(x+y) = 9

x + 4 = 9

Therefore,

x = 9 - 4 = 5

Therefore ,

(x-y) = 5 - 4 = 1