Factorise x^2 - 2X -15

Question

lgbasallote · Answer

hint break down the middle term

x^2 - 5x + 3x - 15

lgbasallote · Answer

does that help?

anonymous · Answer

how does that help? Are you suppose to complete the square?

anonymous · Answer

That  does'nt help at all!

mathslover · Answer

$$\huge{x^2-2x-15}$$
$$\huge{x^2+3x-5x-15}$$
$$\huge{x(x+3)-5(x+3)}$$
can u do further ?

mathslover · Answer

Note that : $$\large{a(b+c)-d(b+c)=(a-d)(b+c)}$$
This property is known as : inverse of distributive property

cherylim23 · Answer

Alternatively, complete the square. It works all the time, despite getting fractions at some other times.
x^2 - 2x -15
= (x- 2/2)^2 - (2/2)^2 - 15
= (x-1)^2 - 1 - 15
= (x-1)^2 - 16
Use difference of two squares,
= (x-1+4)(x-1-4)
= (x+3)(x-5)

anonymous · Answer

x^2 - 2X -15

(x+a)(x+b)

a and b are two numbers that when you multiply them together you get -15
and when you add them together you -2

anonymous · Answer

Simple as that