Solve quadratic equations by factoring
Solve a quadratic equation ax^2 + bx + c = 0 by factoring. Unlimited questions, five difficulty levels, and a full worked solution every time, included free with weekly lessons.
Try one
Solve the equation by factoring.
x2 - 5x + 4 = 0
- x = 1 or x = 4
- x = −1 or x = 4
- x = 1 or x = −4
- x = −1 or x = −4
Answer: x = 1 or x = 4
See one solved, step by step
Solve the equation by factoring.
x2 - x - 20 = 0
- x = 4 or x = −5
- x = −4 or x = 5
- x = −4 or x = −5
- x = 4 or x = 5
📘 Worked solution
1x2 - x - 20 = 0Start with the equation set equal to zero - that's what lets factoring work.
2(x - 5)(x + 4) = 0Factor the trinomial: the roots 5 and -4 give factors (x - 5) and (x + 4).
3x = −4 or x = 5A product is zero only when one of the factors is zero, so set each factor to zero and solve.
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