Question

Solve this:
a^2 +9a =0

Answer 1

Use the quadratic formula

=

−

±

2

−

4

√

2

x=\frac{-{\color{#e8710a}{b}} \pm \sqrt{{\color{#e8710a}{b}}^{2}-4{\color{#c92786}{a}}{\color{#129eaf}{c}}}}{2{\color{#c92786}{a}}}

x=2a−b±b2−4ac

Once in standard form, identify a, b and c from the original equation and plug them into the quadratic formula.

2

+

9

=

0

a^{2}+9a=0

a2+9a=0

=

1

a={\color{#c92786}{1}}

a=1

=

9

b={\color{#e8710a}{9}}

b=9

=

0

c={\color{#129eaf}{0}}

c=0

=

−

9

±

9

2

−

4

⋅

1

⋅

0

√

2

⋅

1

a=\frac{-{\color{#e8710a}{9}} \pm \sqrt{{\color{#e8710a}{9}}^{2}-4 \cdot {\color{#c92786}{1}} \cdot {\color{#129eaf}{0}}}}{2 \cdot {\color{#c92786}{1}}}

a=2⋅1−9±92−4⋅1⋅0

2 Simplify

3

Separate the equations

4

Solve

Solution

=

0

=

−

9

Answer 2

a^2 + 9a = 0

a^2=-9a

a= root 9

a = 3