Step 1: Simplify both sides of the equation.
x
=
−
0.2
x
2
+
400
Step 2: Subtract -0.2x^2+400 from both sides.
x
−
(
−
0.2
x
2
+
400
)
=
−
0.2
x
2
+
400
−
(
−
0.2
x
2
+
400
)
0.2
x
2
+
x
−
400
=
0
Step 3: Use quadratic formula with a=0.2, b=1, c=-400.
x
=
−
b
±
b
2
−
4
a
c
2
a
x
=
−
(
1
)
±
(
1
)
2
−
4
(
0.2
)
(
−
400
)
2
(
0.2
)
x
=
−
1
±
321
0.4
x
=
42.29118216792229
,
−
47.29118216792229
