please help me!

[fefe1221]

If 3x is one factor of 3xsquared-9x, what is the other factor??



If (x-4) is a factor of xsquared-x-w=0, then the value of w is?


The senior class at South High School consists of 250 students. Of these students, 130 have brown hair, 160 havebrwon eyes, and 90 have both brown hair and brown eyes. How many members of the senior class have neither brwon hair nor brown eyes? (50 students?)

On the first six tests in her social studies course, Jerelyn's score were 92, 78, 86, 92, 95, and 91. What score does she need to make the average exactly a 90? (96?)

 

[tkhunny]

If 3x is one factor of 3xsquared-9x, what is the other factor??

Several Words: The Distributive Property of Multiplication over Addition

3x^2 - 9x = 3*(x^2 - 3x) = 3x*(x-3)

If (x-4) is a factor of xsquared-x-w=0, then the value of w is?

What do you know about such problems? Have you studied factoring? Completing the Square? The Quadratic Formula? FOIL?

x^2 - x - w = 0
Since 'x-4' is a factor, it MUST have another convenient factor.
x^2 - x - w = (x-4)*(x-A) = x^2 - (4+A)x + 4*A

Compare corresponding parts' coeficients.
-(4+A) = -1 ==> 4+A = 1 ==> A = -3

4*A = -W ==> 4(-3) = -W ==> 12 = W

The senior class at South High School consists of 250 students. Of these students, 130 have brown hair, 160 havebrwon eyes, and 90 have both brown hair and brown eyes. How many members of the senior class have neither brwon hair nor brown eyes? (50 students?)

Just draw a map.
Brown Hair: 130
Brown Eyes: 160
Both: 90
Brown Hair Only: 130-90 = 40
Brown Eyes Only: 160-90 = 70
Total Students Accounted for: 90+40+70 = 200
Neither: 250-200 = 50 <== You got it!

On the first six tests in her social studies course, Jerelyn's score were 92, 78, 86, 92, 95, and 91. What score does she need to make the average exactly a 90? (96?)

Rule of thumb, either thumb: If you don't know a quantity, give it a name. Then we can talk about it.

What score does she need? Call it 'X'. (Call it 'Steve' if you like, but 'X' is usually more convenient.)

What is the average? (92+78+86+92+95+91+X)/7 = 90

Solve for X. I get 96. <== You got it again!