Ineed with these two problems. need an explanation, steps, and an answer.

Let be the scores of the first 8 quizzes. We know that the average of these scores is 85, so we have

The average of the first 9 scores is 81, and it is given by

But we know that the sum of the first 8 is 680:

And we can solve for the nineth score: multiply both sides by 9:

Subtract 680 from both sides:

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.

the answer to this is 4340

hope this if needed hmu