NEED HELP!!!!!!!!!!!!!!!

Which factorizations can be used to identify the real zeros of the function f(x)=-20x^2+23x-6 ?

A. (-10x+2)(2x+3)
B. -(10x+2)(2x-3)
C. -(4x-3)(5x+2)
D. -(4x-3)(5x-2)

Respuesta :

It's D, it's the only one where it has a -6 at the end other than A, but if you look at the A when distributed there isn't a 23x

Answer:

Option D. [tex]-(4x-3)(5x-2)[/tex]

Step-by-step explanation:

we have

[tex]f(x)=-20x^{2}+23x-6[/tex]

Equate the function to zero

[tex]-20x^{2}+23x-6=0[/tex]

Group terms that contain the same variable, and move the constant to the opposite side of the equation

[tex]-20x^{2}+23x=6[/tex]

Factor the leading coefficient

[tex]-20(x^{2}-(23/20)x)=6[/tex]

Complete the square. Remember to balance the equation by adding the same constants to each side

[tex]-20(x^{2}-(23/20)x+(529/1,600))=6-(529/80)[/tex]

[tex]-20(x^{2}-(23/20)x+(529/1,600))=-(49/80)[/tex]

[tex](x^{2}-(23/20)x+(529/1,600))=(49/1,600)[/tex]

Rewrite as perfect squares

[tex](x-(23/40))^{2}=(49/1,600)[/tex]

[tex](x-(23/40))=(+/-)(7/40)[/tex]

[tex]x=(23/40)(+/-)(7/40)[/tex]

[tex]x=(23/40)(+)(7/40)=30/40=3/4[/tex]

[tex]x=(23/40)(-)(7/40)=16/40=2/5[/tex]

therefore

[tex]-20x^{2}+23x-6=-20(x-(3/4))(x-(2/5))[/tex]

[tex]-20x^{2}+23x-6=-(5)(4)(x-(3/4))(x-(2/5))[/tex]

[tex]-20x^{2}+23x-6=-(4x-3)(5x-2)[/tex]