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Can u help me with this thank you Which expression is the completely factored form of the expression x2-3x-28 .

Can u help me with this thank you Which expression is the completely factored form-example-1

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Answer:

( x + 4)( x -7 )

Step-by-step explanation:

We are asked to factor the following expression.


x^2-3x-28

Meaning, we have to write the above in the following form


(x+a)(x+b)

Now, expanding the above gives


(x+a)(x+b)=x^2+(a+b)x+ab

Upon comparing the RHS of the above with our expression, we find that


\begin{gathered} a+b=-3 \\ ab=-28 \end{gathered}

In other words, what two numbers sum to -3 and have a product of -28?

Well, if our two numbers are -4 and 7 then


\begin{gathered} 4*-7=-28 \\ 4+-7=-3 \end{gathered}

Hence, the factored form of our expression is


(x+4)(x-7)

User Shoaib Nomani
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