Question

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

Answer 1

`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"`