
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
June 12th, 2018, 09:35 AM  #1 
Newbie Joined: Jun 2018 From: Jersey Posts: 1 Thanks: 0  Confusion on algebra question please help
Right so the question states that the volume of a triangular prism is 24cm cubed. it gave the length of the triangular prism as 5cm and the base of the cross sectional area 6. It wanted me to work out the height. So I converted it to algebra: (6*h/2) * 5 = 24cm^3 From there I went to: 6*h * 10 = 48cm^3 and from there I solved it down to h = 0.8cm However the answer is infact 1.6 cm (which agrees with all the other variables), the difference coming from the 10 being a five. My question is why on earth would the 5 stay a five when the entire equation must be multiplied by 2 to eliminate the /2??? Sorry if it's really obvious and I'm just not seeing it, thanks in advance. 
June 12th, 2018, 09:50 AM  #2 
Senior Member Joined: Aug 2012 Posts: 2,047 Thanks: 585 
If I give you 1/2 * 4 and I ask you to multiply that expression by 2, what do you get? 1/2 * 4 = 2, so multiplying by 2 gives you 4. If you multply 1/2 by 2 AND you multiply 4 by 2 you are in effect multiplying the whole expression by 4. It's already a multiplication. You are perhaps thinking that if it were 1/2 + 4 then you'd multiply both terms by 2. But when it's 1/2 x 4, you only want to multiply the expression by 2, once. 

Tags 
algebra, confusion, geometry, question, trigonometry 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Mechanics basic question confusion.  taylor_1989_2012  Physics  2  April 4th, 2013 05:50 AM 
Confusion logics question  ludicrum  Applied Math  2  October 9th, 2012 11:48 AM 
series question  might be an algebra question  aaronmath  Calculus  2  December 17th, 2011 08:28 PM 
Algebra question  jonas  Algebra  3  June 3rd, 2011 12:44 PM 
Algebra confusion , linear equation  roncarlston  Algebra  9  March 15th, 2009 11:54 AM 