Question

Give a answer quickly ​

Answer 1

As we know diagonals of parallelogram bisect each other

So mid point of AC = mid point of BD

A( -2,-1) B ( a,0) C( 4,b) D ( 1,2)

( -2 +4)/2, ( -1 + b)/2 = ( a+1)/2, ( 0+2)/2

Compare

2/2 = a+1/2

a+1 = 2

a= 1

and

y coordinate

-1 + b)/2 = 2/2 = 1

-1 + b= 2

b= 3