Use the power rule
a
m
a
n
=
a
m
+
n
a
m
a
n
=
a
m
+
n
to combine exponents.
−
56
+
21
i
+
48
i
−
18
i
1
+
1
-
56
+
21
i
+
48
i
-
18
i
1
+
1
Add
1
1
and
1
1
to get
2
2
.
−
56
+
21
i
+
48
i
−
18
i
2
-
56
+
21
i
+
48
i
-
18
i
2
Rewrite
i
2
i
2
as
−
1
-
1
.
−
56
+
21
i
+
48
i
−
18
⋅
−
1
-
56
+
21
i
+
48
i
-
18
⋅
-
1
Multiply
−
18
-
18
by
−
1
-
1
to get
18
18
.
−
56
+
21
i
+
48
i
+
18
-
56
+
21
i
+
48
i
+
18
Add
−
56
-
56
and
18
18
to get
−
38
-
38
.
−
38
+
21
i
+
48
i
-
38
+
21
i
+
48
i
Add
21
i
21
i
and
48
i
48
i
to get
69
i
69
i
.
−