Question

Factorise : 4x^2+15x =0​

Answer 1

Answer:

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.

4

2

+

1

5

=

0

4x^{2}+15x=0

4x2+15x=0

=

4

a={\color{#c92786}{4}}

a=4

=

1

5

b={\color{#e8710a}{15}}

b=15

=

0

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

c=0

=

−

1

5

±

1

5

2

−

4

⋅

4

⋅

0

√

2

⋅

4

x=\frac{-{\color{#e8710a}{15}} \pm \sqrt{{\color{#e8710a}{15}}^{2}-4 \cdot {\color{#c92786}{4}} \cdot {\color{#129eaf}{0}}}}{2 \cdot {\color{#c92786}{4}}}

x=2⋅4−15±152−4⋅4⋅0

2