Question

if X-Y= -9 and XY = -20,THEN FIND x2 + y2

Answer 1

X-Y=-9 EQUATION (1)

XY=-20 EQUATION (2)

NOW FIRST OF ALL WE FIND THE VALUE X FROM EQUATION FIRST

X-Y=-9

X=Y-9 EQUATION (3)

NOW THE VALUE OF X WE PUTTING IN EQUATION (2)

XY=-20

FROM EQUATION (3)

(Y-9)Y=-20

Y2 -9Y =-20

Y2-9Y+20=0

BY FACTORISATION METHOD

Y2 -5Y-4Y+20=0

Y(Y-5)-4(Y-5)=0

(Y-5)(Y-4)=0

Y-5=0,Y-4=0

Y=5,Y=4

IF WE TAKE Y=5 IN EQUATION 1

X-Y=-9

X-5=-9

X=-9+5

X=-4

IF WE TAKE Y=5 THEN THE VALUE OF X AND Y IS X=-4,Y=5

SO THAT X2+Y2

16+25

41

ANSWER

IF WE TAKE THE VALUE Y=4 WE PUTTING IN EQUATION 1

X-Y=-9

X-4=-9

X=-5

SO THAT IN THAT CONDITION

X2+Y2

25+16

41 THIS IS CORRECT ANSWER