help please

Question

Select The appriximate values of x that are solutions to f(x)=0, where f(x)= -5x^2 +  4x + 9

Answer 1

f(x)=-5x²+4x+9

look at -5 and 9, their sum is 4

factor -5 into 1(-5) and factor 9 into 1(9)

(-5x+9)(x+1)=0

-5x+9=0

-5x=-9

x=9/5

x+1=0

x=-1

Answer 2

You will need to use the quadratic equation (QE) to find the roots of this quadratic, using:

 

a= -5

b= 4

c= 9

 

When you put these into the Q. E. you should get these 2 solutions:

9/5

-1

 

You can check that  these are solutions by putting into the original equation.