Respuesta :

19allenethm

Answer:

[tex]-11b^2+8b-4[/tex]

Step-by-step explanation:

We can substitute in our expressions for P and Q to get

[tex]P=-4b^2+6b-9\\Q=7b^2-2b-5\\\\(-4b^2+6b-9)-(7b^2-2b-5)[/tex]

Next, we need to distribute the negative to the values within the parenthesis. Then we can combine like terms in order to get our answer

[tex](-4b^2+6b-9)-(7b^2-2b-5)\\\\-4b^2+6b-9-7b^2+2b+5\\\\-11b^2+8b-4[/tex]

mathstudent55

Answer:

-11b^2 + 8b - 4

Step-by-step explanation:

(-4b^2 + 6b - 9) - (7b^2 - 2b - 5) =

Drop the first set of parentheses because it is unnecessary. To drop the second set of parentheses, you must distribute the negative sign. That means you must change every sign inside the second set of parentheses.

= -4b^2 + 6b - 9 - 7b^2 + 2b + 5

Now, group like terms.

= -4b^2 - 7b^2 + 6b + 2b - 9 + 5

Finally, combine like terms.

= -11b^2 + 8b - 4

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