Homework Help: Please Check My Math Work

Posted by [C]razy Baby.-[iloveyou] (Margie) on Friday, February 9, 2007 at 7:10pm.

Hi. - I solved this problem,but I am not sure if it is correct.If you can please tell me if it is right or if it is wrong what is wrong with it.:
6y^2-54=
(3y-6)(2y+9)

*Many of you may be are wondering why my title is,"[C]razy Baby. - [Iloveyou]"it is becuase of the boy that i love.His name starts with"c" but he doesn't know I love him.

Your answer was wrong.

6y^2-54 = 6(y^2 - 9) = 6(y+3)(y-3)

When you write down an expression like:

(3y-6)(2y+9)
try to check what the coefficient of y is. To get something proportional to y you must either take the 3y from the first bracket and multiply that with the 9 from the second bracket or you must take the 2y from the second bracket and multiply that by the -6 from the first bracket.

If you add up the two possibilities you get the total contribution of y. You find that it is 15 y.

I've read on this forum that students are recommended to use the so-called FOIL method, which is just writing down the terms in a certain order. But given that you did not see that your answer was wrong, I think that you should not use such methods.

You should just do excercises until you can look at an equation and just "see" what comes out.

thanks.- can you help me with my other problem.?

!

0.30 times 79

0.30 times 79

no im sorry

4n + 17 + 50
4n = 33
how do i 'check' this problem?

4+5

Please Check My Math Work - mariel, Sunday, July 27, 2008 at 9:07pm
Solve the following algebraically. Trial and error is not an appropriate method of solution. You must show all of your work and write answers in rational form.

3 x + 7 = 9

Answer: x = 2/3

Show your work here: 3 x + 7 = 9
-7 - 7
3/3 x = 2/3
X = 2/3

b)
Answer: x= -2

Show your work here: -3(x +5) + 3 = 12
-3x+15 +3 =12
- 3 x + 18 = 12
- 18 - 18
3/3x = -6/3
X = -2

C)
Answer: x = 12/5

Show your work here: 3(2/3 x+ 1/6x)=2.3 2x + ½ x = 6 x =6 x =5 x= 12/5

d)
Answer: x = - 7

Show your work here: -2 x – 4 < 10 + 4 +4 -2/-2 x < 14/-2 x = - 7

2)

a) Solve for y
Answer: y = 2 – 3 x

Show your work here: 3 x + 4 y = 8
-3 x 3 x
4/4 y = 8 -3 x
Y = 2 – 3 x

b) When graphed this equation would be a line. By examining your answer to part a, what is the slope and y-intercept of this line?
Slope = -3
Y-intercept = 2
c) Using your answer from part a, find the corresponding value of y when x =8.
Answer: y = 22

Show your work here: x =8 y = 2 -3x y = 2 – 3 (8) y = 2 -24 y =22
3) The following graph shows Mary’s salary from the year 2004 to the year 2007. She was hired in the year 2004; therefore x = 0 represents the year 2004.

a) List the coordinates of any two points on the graph in (x, y) form.
(x3, y¹ 5), (x²1-, 1y²)
b) Find the slope of this line:
Answer: m =y² - y¹
X² - x¹
Show your work here: m= - 1 + ¯5 = ¯6
1 + ¯3 = ¯2 slope = 3
c) Find the equation of this line in slope-intercept form.
Answer: y =3 x + 1
Show or explain your work here: y = m x + b
Y = 3 x + 1
d) If Mary’s salary trend continued, what would her salary be in the year 2014? Show how you obtained your answer using part c).
Answer: Mary salary will be 43,500 in 2004.
Show or explain your work here: m x b = y
1500(7) + 33,000 = y 10,500 +33,000= y= 43,500

4) Suppose that the width of a rectangle is 2 inches shorter than the length and that the perimeter of the rectangle is 80. P= 80 x = width x +2 = length
P = 2 (1) + 2 (w)
a) Set up an equation for the perimeter involving only L, the length of the rectangle. Answer: x + 2 = length
b) Solve this equation algebraically to find the length of the rectangle. Find the width as well.
Answer: Length _x = 2 = 19 + 2= 21, Width _x = 19
a) Show your work here: 2 (x = 2) + 2x = 80 2x + 4 + 2 x = 80 4x + 4 = 80 -4 -4 4x/4 = 76/4 x = 19 width = x= 19 length = x = 2 =19 + 2 = 21

5) A tennis club offers two payment options:
Option1: $32 monthly fee plus $3/hour for court rental
Option 2: No monthly fee but $6.50/hour for court rental.
Let x = hours per month of court rental time.
a) Write a mathematical model representing the total monthly cost, C, in terms of x for the following:
Option 1: C=32 + 3 (x)
Option 2: C=_$6.50 (x)
b) How many hours would you have to rent the court so that the monthly cost of option 1, is less than option 2. Set up an inequality and show your work algebraically using the information in part a. Round to 3 decimal places if necessary.
Answer:
Show your work here:

6) Plot the following points on the given rectangular coordinate system by clicking on the given dots and dragging them.

If you were to connect these points with a line, where would the y-intercept be located? Give answer in (x, y) form.

(___, ___)
- math - Emily, Sunday, November 30, 2008 at 3:19pm
  -11-13

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