How do you solve #x^2-2x-15=0#?

1 Answer
Jim G.
Nov 7, 2017

#x=-3" or "x=5#

Explanation:

#"given the equation in standard form"#

#•color(white)(x)ax^2+bx+c=0#

#"factorise by considering the factors of the product a-c"#
#"which sum to + b"#

#"the factors of - 15 which sum to - 2 are - 5 and + 3"#

#rArr(x-5)(x+3)=0#

#"equate each factor to zero and solve for x"#

#x+3=0rArrx=-3#

#x-5=0rArrx=5#

#rArrx=-3" or "x=5" are the solutions"#

Related questions
See all questions in Comparing Methods for Solving Quadratics
Impact of this question
4917 views around the world
You can reuse this answer
Creative Commons License