berilah saya pembahasan dari soal-soal tersebut

misal 1/2a-b = x, dan 1/2a+b = y
2x + 7y = 3
1x - 7y = 0
---------------- +
3x = 3
x = 1
2(1) + 7y = 3
7y = 1
y = 1/7
ganti ke fungsi awal
x = 1/(2a-b)
1 = 1/(2a-b)
2a - b = 1
y = 1/(2a+b)
1/7 = 1/(2a+b)
2a + b = 7
eliminasi
2a + b = 7
2a - b = 1
----------------+
4a = 8
a = 2
2(2) - b = 1
4 - b = 1
b = 3

a² + 2b = 2² + 2(3) = 10