P(x) = ax+b
P(x-1) = a.(x-1) + b
P(x-1) = ax-a + b
P(x) + P(x-1) = ax+b +ax -a+b
2ax+2b-a = 4x+3
2a = 4
a = 2
2b-a = +3
2b-2 = +3
2b = 5
b = [tex] \frac{5}{2} [/tex]
P(x) = 2x + [tex] \frac{5}{2} [/tex]
P(1) = 2.1 + [tex] \frac{5}{2} [/tex]
→ 2 + [tex] \frac{5}{2} [/tex]
→ [tex] \frac{9}{2} [/tex]
