IXL - Solve a quadratic equation using the quadratic formula (Geometry practice)

Solve using the quadratic formula.

6m² + 4m − 5 = 0

Write your answers as integers, proper or improper fractions in simplest form, or decimals rounded to the nearest hundredth.

m = or m =

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Learn with an example

question

Solve using the quadratic formula.

9f² + 4f − 1 = 0

Write your answers as integers, proper or improper fractions in simplest form, or decimals rounded to the nearest hundredth.

f = or f =

key idea

The quadratic formula is

^–b ± b² − 4ac

where a ≠ 0. It can be used to solve a quadratic equation (ax² + bx + c = 0).

solution

Use the quadratic formula to solve 9f² + 4f − 1 = 0.

^–b ± b² − 4ac

Plug in a = 9, b = 4, and c = ^–1

^–4 ± 4² − 4(9)(^–1)

2(9)

Plug in a = 9, b = 4, and c = ^–1

Multiply

^–4 ± 16 + 36

Multiply

Add

^–4 ± 52

Add

Split ± into + or -

^–4 + 52

^–4 − 52

Split ± into + or -

Simplify and round to the nearest hundredth

≈

0.18 or f ≈ ^–0.62

Simplify and round to the nearest hundredth

Looking for more? Try these:

Lesson: The quadratic formula

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Not feeling ready yet? These can help:

K.9Evaluate rational expressions

K.8Evaluate radical expressions

Z.5Solve a quadratic equation by completing the square

Lesson: The quadratic formula

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