My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Thanks Tree2Thanks
  • 1 Post By agentredlum
  • 1 Post By the john
Reply
 
LinkBack Thread Tools Display Modes
April 5th, 2014, 08:19 AM   #1
Newbie
 
Joined: Feb 2014

Posts: 17
Thanks: 0

Help with equation

Hi,

I'm trying to solve these equations . Can someone help with them?
No multiplication signs and x is the number.

3x −5 = 3 + 5x

2(x − 9) = 6+ x/2

Thanks.
Rob158 is offline  
 
April 5th, 2014, 10:50 AM   #2
Math Team
 
agentredlum's Avatar
 
Joined: Jul 2011
From: North America, 42nd parallel

Posts: 3,372
Thanks: 233

1) $ 3x - 5 = 3 + 5x $

Subtract $3x$ from both sides

$ -5 = 3 + 2x $

Subtract $3$ from both sides

$ -8 = 2x $

Divide both sides by $2$

$ -4 = x $

Check work in original

$$3(-4) - 5 = 3 + 5(-4)$$

$$-12 - 5 = 3 - 20$$

$$-17 = -17$$

2) $2(x - 9) = 6 + \dfrac{x}{2}$

Use the distributive property on the left hand side

$ 2x - 18 = 6 + \dfrac{x}{2}$

Multiply everything by 2 so we can clear the fraction

$4x - 36 = 12 + x $

Subtract $x$ from both sides

$3x - 36 = 12 $

Add 36 to both sides

$3x = 48$

Divide both sides by 3

$x = 16$

Check work

$$2(16 - 9) = 6 + \dfrac{16}{2}$$

$$2(7) = 6 + 8$$

$$14 = 14$$

Thanks from MarkFL
agentredlum is offline  
April 6th, 2014, 01:55 AM   #3
Senior Member
 
Joined: Mar 2014

Posts: 112
Thanks: 8

If I didn't get the answers x = -4, 16 respectively then I would've failed the SAT mathematics. I'm not talking about you, Rob158; again I'm talking about me.
If the intended problem for the second one was 2(x - 9) = (6 + x)/2 then x = 14.
Thanks from agentredlum
the john is offline  
April 6th, 2014, 05:59 PM   #4
Senior Member
 
Joined: Mar 2014

Posts: 112
Thanks: 8

Again I'm not smart.
the john is offline  
April 13th, 2014, 05:32 AM   #5
Newbie
 
Joined: Feb 2014

Posts: 17
Thanks: 0

Quote:
Originally Posted by the john View Post
If I didn't get the answers x = -4, 16 respectively then I would've failed the SAT mathematics. I'm not talking about you, Rob158; again I'm talking about me.
If the intended problem for the second one was 2(x - 9) = (6 + x)/2 then x = 14.
I'm not sure what you mean. I know I am very bad at maths if that is what you mean, but I want to learn.


Quote:
Originally Posted by agentredlum View Post
1) $ 3x - 5 = 3 + 5x $

Subtract $3x$ from both sides


Many thanks.
I have been practicing.
Rob158 is offline  
April 18th, 2014, 08:06 PM   #6
Senior Member
 
Joined: Mar 2014

Posts: 112
Thanks: 8

You're not bad at mathematics.
the john is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
equation



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Show that an equation satisfies a differential equation PhizKid Differential Equations 0 February 24th, 2013 11:30 AM
simplify equation to get a quadratic equation mich89 Algebra 3 January 9th, 2013 02:22 PM
Tangent equation of a tricky equation xujack88 Calculus 8 December 11th, 2009 08:04 PM





Copyright © 2019 My Math Forum. All rights reserved.