How do you solve #-24r - 28\leq - 4( 5r + 4)#?

1 Answer
Jul 29, 2017

See a solution process below:

Explanation:

First, expand the term on the right side of the inequality by multiplying each term within the parenthesis by the term outside the parenthesis:

#-24r - 28 <= color(red)(-4)(5r + 4)#

#-24r - 28 <= (color(red)(-4) xx 5r) + (color(red)(-4) xx 4)#

#-24r - 28 <= -20r + (-16)#

#-24r - 28 <= -20r - 16#

Next, add #color(red)(24r)# and #color(blue)(16)# to each side of the inequality to isolate the #r# term while keeping the inequality balanced:

#color(red)(24r) - 24r - 28 + color(blue)(16) <= color(red)(24r) - 20r - 16 + color(blue)(16)#

#0 - 12 <= (color(red)(24) - 20)r - 0#

#-12 <= 4r#

Now, divide each side of the equation by #color(red)(4)# to solve for #r# while keeping the equation balanced:

#-12 /color(red)(4) <= (4r)/color(red)(4)#

#-3 <= (color(red)(cancel(color(black)(4)))r)/cancel(color(red)(4))#

#-3 <= r#

To state the solution in terms of #r# we can reverse or "flip" the entire inequality:

#r >= -3#