8x^(2)+16x=42 completeing the square

16
x
2
+
16
x
=
42
Step 2: Subtract 42 from both sides.
16
x
2
+
16
x
−
42
=
42
−
42
16
x
2
+
16
x
−
42
=
0
For this equation: a=16, b=16, c=-42
16
x
2
+
16
x
+
−
42
=
0
Step 3: Use quadratic formula with a=16, b=16, c=-42.
x
=
−
b
±
b
2
−
4
a
c
2
a
x
=
−
(
16
)
±
(
16
)
2
−
4
(
16
)
(
−
42
)
2
(
16
)
x
=
−
16
±
2944
32
x
=
−
1
2
+
1
4
46
or
x
=
−
1
2
+
−
1
4
46

x
=
−
1
2
+
1
4
46
or
x
=
−
1
2
+
−
1
4
46

The biological half-life or terminal half-life of a substance is the time it takes for a substance to lose half of its amount. Having 5 half lives would be five times the half life. Therefore, 5 half lives of 14-C is equal to 28650 years. Hope this answers the question. Have a nice day.