Dna i need your help buddy

[redback]

What is..

9xy + 8y - 4y (squared) + 9y - 2x (squared)y

and

x(x+4) = 21

can you explain how you work it out. I have a bunch of other stuff but i dont think i can even type it on a standard keyboard.

[Shibby]

What is..

9xy + 8y - 4y (squared) + 9y - 2x (squared)y

and

x(x+4) = 21

can you explain how you work it out. I have a bunch of other stuff but i dont think i can even type it on a standard keyboard.

Check out this website Algebra Homework Help, Algebra Solvers, Free Math Tutors

you will have a few easy conversions like changing 4y squared to 4y * 4y or 4y(y)

[the art of war]

man i hated that shit and math was only thing i was good at lol. It's so damn boring until geometry. And then it just gets tedious lol.

[Scrumhalf]

What is..

9xy + 8y - 4y (squared) + 9y - 2x (squared)y

and

x(x+4) = 21

can you explain how you work it out. I have a bunch of other stuff but i dont think i can even type it on a standard keyboard.

1. For the 1st one, you need to group similar variables together. All x's go together, all xy's go together, etc.

So, the expression 9xy + 8y -4y^2 +9y - 2x^2

becomes 9xy +17y -4y^2 -2x^2

You can't simplify it any further.

2. You need to invoke the distributive law, which states that:

a(b+c) = ab + ac

So, x(x+4) = 21

becomes

x^2 + 4x -21 = 0

This is a simple quadratic equation of the form ax^2 + bx + c = 0.

The two solutions for this equation is:

x = (-b + sqrt (b^2 - 4ac))/2a and (-b - sqrt(b^2 - 4ac))/2a

Since in your case, a = 1, b = 4 and c = -21,

The solutions are:

x = (-4 + sqrt (16 + 84))/2 and x = (-4 - sqrt (16 + 84))/2

or X = 3 and x = -7.

You can test it out by plugging x back into the equation and checking.

For example, if x = 3 ,

3 x (3+4) = 21, which checks out

or

-7 (-7 +4) = 21 which checks out again.

[the art of war]

shouldn't you be running :D

[Scrumhalf]

Gym in 15 minutes.... just getting ready to head out the door... :)

[dna9488]

1. For the 1st one, you need to group similar variables together. All x's go together, all xy's go together, etc.

So, the expression 9xy + 8y -4y^2 +9y - 2x^2

becomes 9xy +17y -4y^2 -2x^2

You can't simplify it any further.

2. You need to invoke the distributive law, which states that:

a(b+c) = ab + ac

So, x(x+4) = 21

becomes

x^2 + 4x -21 = 0

This is a simple quadratic equation of the form ax^2 + bx + c = 0.

The two solutions for this equation is:

x = (-b + sqrt (b^2 - 4ac))/2a and (-b - sqrt(b^2 - 4ac))/2a

Since in your case, a = 1, b = 4 and c = -21,

The solutions are:

x = (-4 + sqrt (16 + 84))/2 and x = (-4 - sqrt (16 + 84))/2

or X = 3 and x = -7.

You can test it out by plugging x back into the equation and checking.

For example, if x = 3 ,

3 x (3+4) = 21, which checks out

or

-7 (-7 +4) = 21 which checks out again.

Thanks DNA :P

[redback]

thanks heaps guys, awesome work scrum, still trying to get my head around it tho

[Bouncer]

thanks heaps guys, awesome work scrum, still trying to get my head around it tho

you like 40. why you doing highschool work? :rofl:

[the art of war]

you like 40. why you doing highschool work? :rofl:

hater. who put you in control of the sandlot. :hibb:

[dna9488]

thanks heaps guys, awesome work scrum, still trying to get my head around it tho

its not that difficult, just tricky. Math isn't everyone's strong point. So just keep practicing and you'll be fine :)

[redback]

its not that difficult, just tricky. Math isn't everyone's strong point. So just keep practicing and you'll be fine :)

lol i still got physics and chemistry to go yet.

[Bouncer]

lol i still got physics and chemistry to go yet.

what grade you in bro? what period is lunch? :rofl:

[Scrumhalf]

How long did it take you to type that out:P

5 minutes... I'm good.. :agreed:

[dna9488]

lol i still got physics and chemistry to go yet.

If you have any questions about those post them up man, I'll gladly help a brother out :)