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What is the expression in factored form?

-x^2 + 3x + 28

a. (x-7)(x-4)
b. -(x-7)(x+4)
c. (x+4)(x+7)
d. -(x-4)(x+7)

Respuesta :

Answer:

[tex]\boxed{b.\:\:-(x-7)(x+4)}[/tex]

Step-by-step explanation:

The given expression is [tex]-x^2+3x+28[/tex]


We split the middle term to obtain;

[tex]-x^2+7x-4x+28[/tex]


We factor to get;


[tex]-x(x-7)-4(x-7)[/tex]


We factor further to obtain;


[tex]=(x-7)(-x-4)[/tex]

We factor the negative 1 to get;

[tex]=-(x-7)(x+4)[/tex]

Answer:

Choice b is correct answer.

Step-by-step explanation:

Given expression is:

-x²+3x+28

We have to represent above expression in factored form.

Split the middle term of given expression so that the product of two terms should be -28 and their sum be 3.

-x²+7x-4x+28

make two groups and taking common,we get

-x(x-7)-4(x-7)

taking (x-7) as common,we get

(x-7)(-x-4)

As we observed that -1 is common in last term of above expression.

take negative sign as common

-(x-7)(x+4)  which is the answer we required.