in my math book I'm stuck on this algebra question  12r -25 = 4r+7 = ? 

Expert Answers

An illustration of the letter 'A' in a speech bubbles

calling the variable r doesn't necessary implies that r is a radial polar.

It could be the number of racoons ;-)

Approved by eNotes Editorial Team
An illustration of the letter 'A' in a speech bubbles

Indeed the answer is r=4 but to offer further explanation, this is a polar equation where r is the radial coordinate otherwise known as the radius. The equation is that of a circle centered at the origin where r = the radius which is 4.

Approved by eNotes Editorial Team
An illustration of the letter 'A' in a speech bubbles

it is a linear equation.

You may substract 4r on both sides of the equality so that r will appear only on one side.

The equation becomes

`12r-25-4r=4r+7-4r`

if we collect like terms
` 12r-4r=8r`

`8r-25=7`

Add 25 on both side of the equation so that all the constant terms will be on one side.

`8r-25+25=7+25`

Collect like terms

`8r=32`

Divide you equation by 8

`r=32/8=4`

Answer r=4

 

Approved by eNotes Editorial Team
An illustration of the letter 'A' in a speech bubbles

12r - 25 = 4r + 7

We need to solve for r.

Then we will combine terms with r on the left side.

==> 12r - 4r = 7 + 25

==> 8r  = 32

Now we will divide by 8.

==> r= 32/8 = 4

==> r= 4

Then, the answer for the equation is r= 4.

Approved by eNotes Editorial Team
Soaring plane image

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial