1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+)

[mathnoob]

1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+)

I am new to math, and have 2 questions i am having some difficulty with. I need to solve for x for both of these..Can someone help show the steps they would use.

1/2x + 2/3x + 18 = 15

3(x² - x) -4 (x² + x) = -3(x+1)-4(x+)

 

[mathnoob]

Re: I need to solve for x

by the way...here is what i have gotten for the first one so far.


1/2x + 2/3x + 18 = 15
3/6x + 4/6x +18 = 15
7/6x = -3

this is where i am stuck

 

[Denis]

Re: I need to solve for x

1/2x + 2/3x + 18 = 15
3/6x + 4/6x +18 = 15
7/6x = -3

You're doing fine; now multiply each side by 6x

 

[Denis]

Re: I need to solve for x

3(x² - x) -4 (x² + x) = -3(x+1)-4(x+)

Perform the multiplications first; like -3(x+1) = -3x - 3

 

[stapel]

3(x² - x) -4 (x² + x) = -3(x+1)-4(x+)

What is the last bit inside the last set of parentheses on the right-hand side? You've got "-4(x +...)". What belongs in that gap?

Thank you!

 

[mathnoob]

Re: 1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+)

sorry,,it should be

3(x²-x)-4(x²+x)=-3(x+1)-4(x+2) ...this is what i have done so far...unsure if this is right
3x²-3x -4x²-4x = -3x -3 -4x - 8

As for the other one....when i get to the part where I time each side by 6 is where i get confused. Could you show me the steps of multiplying each side? and the answer so I can understand this better. thanks

7/6x = -3

 

[stapel]

sorry,,it should be 3(x²-x)-4(x²+x)=-3(x+1)-4(x+2)

...this is what i have done so far...unsure if this is right

3x²-3x -4x²-4x = -3x -3 -4x - 8

Now gather everything together on one side of the "equals" sign, combine the "like" terms, and then solve the resulting quadratic equation, perhaps by using the Quadratic Formula.

when i get to the part where I time each side by 6 is where i get confused. Could you show me the steps of multiplying each side?

For worked examples, try here. :wink:

 

[mathnoob]

Re: 1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+2)

for the first question..
i got x= -7/18 can that be right?

and for the second question could somebody show me a breakdown how they would do it to get the answer please?

 

[stapel]

and for the second question could somebody show me a breakdown how they would do it to get the answer please?

How far have you gotten in the instructions, provided earlier? You moved everything over to the left-hand side (so you have "equals zero" on the right-hand side), simplified, plugged into the Quadratic Formula, and... then what? Where are you stuck?

Please be complete, so we can "see" where you're needing some help. Thank you!

 

[mathnoob]

Re: 1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+2)

i have 3(x²-x)-4(x²+x)=-3(x+1)-4(x+2)
3x²-3x-4x²-4x = -3x-3-4x-8
3x²-4x²=-3-8
-1x²= -11
can that be a way to do it? sorry if this is totally wrong.. and as for my above one...am i right in saying that the answer is x=-7/18

 

[Denis]

Re: 1/2x+2/3x+18=15 and 3(x²-x)-4(x²+x)=-3(x+1)-4(x+2)

-1x²= -11

YES; finish it: x^2 = 11 ; x = sqrt(11)

and as for my above one...am i right in saying that the answer is x=-7/18

YES.