How to use the quadratic formula, using the following equation: x^2 + 3x - 4

To begin you must identify the co-efficients of each x term, essentially what number comes before x2 , x and the integer value.

a = 1, b = 3, c = -4 . We then substitute these values into the quadratic formula:  x = ( -b +- SQRT (b2 - 4ac) ) ÷ 2a . For the top half of the formula we end up with:  - 3 +- SQRT (32 - 4 x 1 x (-4)). This simplifies to -3 +- 5 = 2 or -8.

On the bottom of the formula we simply get 2 x 1 = 2. Therefore our 2 answers for x are x = 2 ÷ 2 or x = -8 ÷ 2 which results in x being equal to x = 1 or -4.

OB
Answered by Oliver B. Maths tutor

3166 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

The equation of a curve is y = (x + 3)^2 + 5. Find the coordinates of the turning point.


Work out 2^14 ÷ (2^9)^2 in its simplest form


Differentiate the equation 3x^4+6x^2-7x+2


What is the gradient of the line passing through the point (1,2) and (5,5)? What is the equation of this line? What is the equation of the line perpendicular to this line that passes through the origin (0,0)?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning