Can u help me solve this equation

[Jeanee]

Solve to 3 sf x^2 -5x -2 = 0

I have tried factorising but it will not factorise. Am I doing something wrong?

[DaveD]

Solve to 3 sf x^2 -5x -2 = 0

I have tried factorising but it will not factorise. Am I doing something wrong?

Any question that says solve to a rounded answer is unlikely to factorise so use the quadratic formula.

[Jeanee]

What formula is that?

[DaveD]

The quadratic formula for solving

ax^2+bx+c=0 is

x=(-b+sqrt(b^2-4ac)) / 2a
or
x=(-b-sqrt(b^2-4ac)) / 2a

In your example a=1, b=-5, c=-2
so
x=[5+SQRT((-5)^2-4(1)(-2)) ]/2
= 5.37 (3sf)
and x=[5-SQRT((-5)^2-4(1)(-2)) ]/2
=-0.372

[Jeanee]

Thanks DaveD