In this lesson, we solve equations of the form:
ax2+bx+c=0
using the quadratic formula:
x=2a−b±b2−4ac
The expression under the square root is called the discriminant:
Δ=b2−4ac
It determines the number and type of solutions.
You will learn
- How to identify coefficients a, b, c
- How to compute the discriminant Δ=b2−4ac
- When Δ>0, there are two real solutions
- When Δ=0, there is exactly one solution x=−2ab
- When Δ<0, solutions are complex x=2a−b±i∣Δ∣
Solve:
2x2+3x−2=0
x=2⋅2−3±32−4(2)(−2)=4−3±25=4−3±5
x=21orx=−2
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