Question

plz tell how to solve ans 19​

Answer 1

x+y = 15 --- (i)
xy = 54 --- (ii)

From eq. (i)
x = 15 - y

Substituting in eq. (ii)
(15 - y)y = 54
15y - y^2 = 54
y^2 - 15y + 54 = 0
y^2 - 9y - 6y + 54 = 0
y(y - 9) - 6(y - 9) = 0
(y - 9)(y - 6) = 0
y = 9 or y = 6

When y = 9
x = 15 - y
x = 15 - 9 = 6

When y = 6
x = 15 - y
x = 15 - 6 = 9

Now, when x = 6 and y = 9
x^2 - y^2
= 6^2 - 9^2
= 36 - 81 = - 45

When x = 9 and y = 6
x^2 - y^2
= 9^2 - 6^2
= 81 - 36 = 45

Answer 2

19th solution

x+y=15

so 9+6=15

(xy)=54

9×6=54

so x>y

9>6

therefore

x2-y2= (x+y) (x-y)

(9+6)(9-6)=15×3=45