CÓ Δ❑ = (M + 1)2 – (M – 4) = M2 + 2M + 1 – M + 4 = M2 + M + 5 = M2 + 2
2. Có
Δ
❑
= (m + 1)
2
– (m – 4) = m
2
+ 2m + 1 – m + 4 = m
2
+ m + 5
= m
2
+ 2.m.
1
2
+
1
4
+
19
4
= (m +
1
2. Có
Δ
❑
= (m + 1)
2
– (m – 4) = m
2
+ 2m + 1 – m + 4 = m
2
+ m + 5
= m
2
+ 2.m.
1
2
+
1
4
+
19
4
= (m +
1