solution
1) <span>Expand
</span><span>9x−6−12x
2) </span><span>Gather like terms
</span><span>(9x−12x)−6
3) </span> <span>Simplify
</span><span><span>−3x−6</span></span>
Step-by-step explanation:

While subtracting , the sign of each term of second expression changes & remove the parentheses.
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Combine like terms. Like terms are those which have the same base. Only coefficients of like terms can be added or subtracted.
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In standard from , the expression should be written in such a way that the power of variables goes from highest to lowest.

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The general form of a quadratic (second degree) equation is

, where

is called the Discriminant.
The Discriminant determines how many roots the equation will have as follows:
i) if D>0, the equation has 2 roots.
ii) if D=0, the equation has 1 double root.
iii) if D<0, the equation has no roots.
In our equation,

, a=1, b=-5, c=7
so the discriminant is D=(-5)^2-4*1*7=25-28<0
Thus the equation has no roots.
Remark: the equation has no roots in the Real numbers, but it has 2 roots in a larger set of numbers to be discussed in the future, the Complex numbers.
Answer:
x = 44
Step-by-step explanation:
Opposite angles in a parallelogram are congruent, so ...
104 = 2x +16
88 = 2x . . . . . . subtract 16
44 = x . . . . . . . divide by 2