Since y=x+3 (given)
Put value of y in equation x+y=(-3)
x+x+3=(-3)
2x=(-6)
x=(-3)
Put x=(-3) in x+y=(-3)
(-3)+y=(-3)
y=0
So, x=(-3)
y=0
D=ab-c Theres your answer
a-1<span />
The answer in b next time make sure the picture is clear
A=90
B=53
The reason I am saying this is because you can see the 90 degree angle in A
You're trying to find constants

such that

. Equivalently, you're looking for the least-square solution to the following matrix equation.

To solve

, multiply both sides by the transpose of

, which introduces an invertible square matrix on the LHS.

Computing this, you'd find that

which means the first choice is correct.