Question

LESSON NAME-[Linear equations in two variables]


Activitiy. 9/10​

Answer 1

Disclaimer: There is error in the Q. In (II) there should have been 2x - 3y = 12

5x + 3y = 9 -----(I)

2x - 3y = 12 ----- (II)

Add (I) and (II)

7x = 21

x = 3

Putting the value of x = 3 in (I) we get

5(3)+3y=9⇒15+3y=9⇒3y=9-15=-6⇒y=-2

Thus, (x, y) = (3, -6).

let seemas age be x

sheelas age =x+7

According to the conditions

x+x+7=53

2x+7=53

2x=46

x= 46/2

x= 23.

therefore,

seemas age=x=23

and sheelas age=x+7= 30

Answer 2

activity 9

if x= -3

in equations

x+y= 7

-3+y= 7

y= 10

2) if y= 12

in equations

x+y= 7

x+12=7

x=-5

activity 10

let the age of seema & sheela be x&y

ATQ

x-y=7 (EQ 1)

&

x+y=53 (EQ)

on adding EQ 1 &2 we get

2x=60

x=30

then y= 23

DON'T FORGET TO MARK ME AS BRAIN LIST