Solve 4x² + 2x - 6 = 0
The solutions of 4x² + 2x - 6 = 0 are x = 1 or x = -3/2.
Change a, b or c (whole numbers, a not 0) and the exact solutions follow.
How to work it out
- 1
Write it in standard form a x² + b x + c = 0 and read off the coefficients: a = 4, b = 2, c = -6.
- 2
Work out the discriminant D = b² − 4ac. Its sign tells you how many real solutions there are.
- 3
D is positive, so there are two different real solutions.
- 4
Method 1, factoring. The roots are rational, so the left side factors:
- 5
A product is zero when one of its factors is zero, so set each factor equal to 0 and solve:
- 6
Method 2, The quadratic formula works for every quadratic:
- 7
Simplify to get the solutions:
- 8
Check by putting x = 1 back in: a·x² + b·x + c = 4·(1) + 2·(1) + (-6) = 0 ✓
LaTeX source of the formulas on this page
\[ 4x^2 + 2x - 6 = 0\ \Rightarrow\ x = 1,\ -\frac{3}{2} \]
\[ 4x^2 + 2x - 6 = 0 \]
\[ D = 2^2 - 4\cdot4\cdot(-6) = 4 + 96 = 100 \]
\[ 2\left(x - 1\right)\left(2x + 3\right) = 0 \]
\[ x - 1 = 0 \Rightarrow x = 1\qquad 2x + 3 = 0 \Rightarrow x = -\frac{3}{2} \]
\[ x = \frac{-b \pm \sqrt{D}}{2a} = \frac{-2 \pm \sqrt{100}}{8} \]
\[ x = 1\quad\text{or}\quad x = -\frac{3}{2} \]The parabola y = 4x² + 2x - 6
| x | y |
|---|---|
| -3.25 | 29.75 |
| -2.25 | 9.75 |
| -1.25 | -2.25 |
| -0.25 | -6.25 |
| 0.75 | -2.25 |
| 1.75 | 9.75 |
| 2.75 | 29.75 |
Questions
What are the solutions of 4x² + 2x - 6 = 0?
The solutions of 4x² + 2x - 6 = 0 are x = 1 or x = -3/2.
Does 4x² + 2x - 6 = 0 factor?
Yes: 2(x-1)(2x+3) = 0.
What is the vertex of y = 4x² + 2x - 6?
(-1/4, -25/4). The parabola opens upwards, so this is the minimum.
What are the sum and product of the roots?
Sum = −b/a = -1/2, product = c/a = -3/2.