Astudent has scores of 74%, 78% and 70% on three exams. what score is needed on a fourth exam for the student to earn an average of 80% ?

(74 + 78 + 70 + x) / 4 = 80

Divide each number by 4.

18.5 + 19.5 + 17.5 + x = 80

Add the numbers you know so far.

18.5 + 19.5 + 17.5 = 55.5

You need 24.5.

Now, since we divided all the others by 4, we have to multiply 24.5 by 4 to see what the exam score would be.

24.5 * 4 = 98.

To get an average of 80%, the student would need to get a 98 on their fourth exam.

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.

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.