What you’ll learn
Solve using quadratic formula.
Key idea
Compute the full discriminant and use negative b in the formula numerator.
Signed coefficients, full discriminant, negative b and both numerator branches are independently required.
Worked example
Enter the exact value or ordered values in the format requested below.
Solve 2x²+4x-16=0 with the quadratic formula; enter both roots separated by a comma.
- Signed coefficients a=2,b=4,c=-16; discriminant b²-4ac=144, positive root 12.
- Formula x=(-4±12)/4 yields roots -4, 2; use -b, not b, and retain both branches.
Answer: -4, 2
Quick Check
Evaluate a worked attempt at solve using quadratic formula, identify the first invalid step, and provide the correction.
Solve 3x²+9x-30=0: Step 1 records a=3,b=9,c=-30. Step 2 computes discriminant 441. Step 3 uses x=(9±21)/6, starting with b rather than -b. Locate the first invalid step and correct both roots.