A6 Formulae and Quadratic Equations

Question 1

What can the quadratic formula do?

Answer 1

Solve all quadratic equations.

Question 2

Before using the full quadratic formula, how can you find out of your quadratic equation will factories and has 1, 2 or no solutions?

Answer 2

Use ‘b2 - 4ac’ part of the formula.

If b2 - 4ac =

• Positive: x has 2 solutions
• Negative: x has no solutions
• Equals 0: x has 1 solution

If b2 - 4ac =

• square number: equation factorises
• not a square number: does not factories, use whole formula.

Question 3

What should be done before putting your equation into the quadratic formula?

Answer 3

Make sure your equation is in the form

ax2 + bx + c = 0.

Question 4

How can you rearrange formula?

Answer 4

• Using inverse operations.

Doing the opposite of what has already been done (undoing)

• collect like terms and factorise or expand.