2^3 is equivalent because if you count the number of twos there are in the parentheses its 3.
for these you need to rearrange the equations and do substitutions.
#3 = if x+y=5 then you know x = 5-y
now substitute that equation for x in the 2nd one so x + 2y = 8 becomes
5-y + 2y = 8 2y - y becomes 1y which becomes y then subtract 5 from each side to get y =3
now replace y with 3 in the first equation x = 5-3 so x = 2
so (2,3) is the answer
same type of work for #4
2x-y=6 ,S0 y = 2X+6
so now you have 4x+2(2x+6)=-4
that becomes 4x +4x+12 = -4
8x+8 = 1, x =1
y = 2(1)-6 = -4
so answer is (1,-4)
we are given
absolute value of 2 and 2 3rd and negative 9 over 4
Firstly , we need write it in terms of expression
2 and 2 3rd is

so, we get as

now, we can simplify it
Firstly , we will find common denominator


we can see that
all denominators are same
so, we can combine numerators


..............Answer
Yes it is linear since it's in the standard form Ax+By = C
A = 2
B = -8
C = 16