(4). Simplifying polynomials, help pls:) brainliest involved

Explanation:

To simplify a polynomial, we have to do two things: 1) combine like terms, and 2) rearrange the terms so that they're written in descending order of exponent.

First, we combine like terms, which requires us to identify the terms that can be added or subtracted from each other. Like terms always have the same variable (with the same exponent) attached to them. For example, you can add 1 "x-squared" to 2 "x-squareds" and get 3 "x-squareds", but 1 "x-squared" plus an "x" can't be combined because they're not like terms.

Let's identify some like terms below.

f(x)=−4x+3x2−7+9x−12x2−5x4

Here you can see that -4x and 9x are like terms. When we combine (add) -4x and 9x, we get 5x. So let's write 5x instead:

f(x)=5x+3x2−7−12x2−5x4

Let's do the same thing with the x-squared terms:

f(x)=5x+3x2−7−12x2−5x4

f(x)=5x−9x2−7−5x4

Now there are no like terms left. Our last step is to organize the terms so that x is written in descending power:

f(x)=−5x4−9x2+5x−7

Step-by-step explanation:

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