Question

4x +7y=13
2x-y=-7
solve by cross multiplication method only.​

Answer 1

cross multiplation formula is refer book pg 48

Answer 2

Answer:

x= -2 , y= 3

Step-by-step explanation:

4x+7y=13

4x+7y-13=0— eq ( 1 )

2x-y= -7

2x-y+7=0—eq ( 2 )

Now, solving eq 1 and 2 by cross multiplication method

Eq (1) 4x+7y -3=0

Eq (2) 2x-y+7=0

than,

A1 =4, B1=7 C1= -13

A2= 2, B2= -1 , C2=7

X/ b1×c2-b2×c1 = Y/ c1×a2-c2×a1= 1/ a1×b2-a2×b1

or

x/ b1c2-b2c1 = Y/c1a2-c2a1 = 1/a1b2- a2b1

x/ 7×7-(-1)×(-13) = Y/(-13)×2-7×4 = 1/4×(-1)-2×7

x/49-13 = Y/(-26)-28 = 1/(-4)-14

x/36 = Y/-54 = 1/-18

than,

x/36 = 1/-18

x= 36/ -18

x= - 2

y/ -54 = 1/-18

y = -54/ -18

y= 3