AI generatedAlgebraGCSE Higher / IGCSE Extended

Quadratic formula - decimal answers

Round only the final roots to the requested accuracy.

  • Put the quadratic equal to zero before factorising or using the quadratic formula.
  • Keep both square-root branches. Do not divide by an expression containing , as this can remove a root.
  • Give exact answers unless rounding is requested. In a context, reject only roots that are not permitted.

Example 1

Solve. Give both roots to 2 decimal places.

Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.

Example 2

Solve. Give both roots to 2 decimal places.

Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.

Your turn

Question 1

Solve. Give both roots to 2 decimal places.

Check answer
Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.
Question 2

Solve. Give both roots to 2 decimal places.

Check answer
Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.
Question 3

Solve. Give both roots to 2 decimal places.

Check answer
Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.
Question 4

Solve. Give both roots to 2 decimal places.

Check answer
Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.
Question 5

Solve. Give both roots to 2 decimal places.

Check answer
Identify . Substitute into the quadratic formula.Use brackets around negative values when substituting.Evaluate the discriminant and simplify the denominator.Simplify the surd and split the plus and minus branches.Keep the full calculator value. Round this root to 2 decimal places.Keep the full calculator value. Round this root to 2 decimal places.
← All Algebra cardsReport a mistake