How do you solve #3(x+5) +6 = 15#?

2 Answers
Jun 7, 2016

Answer:

#color(blue)(x=-2#

Explanation:

#3 ( x+5) + 6 = 15#

#color(blue)((3)) * ( x+5) + 6 = 15#

#color(blue)((3)) * ( x) + color(blue)((3)) *(5) + 6 = 15#

#3x + 15 + 6 = 15#

#3x + 21 = 15#

#3x = 15 - 21 #

#3x = -6 #

#x = (-6)/3#

#color(blue)(x=-2#

Jun 7, 2016

Answer:

Just in case you need further explanation

#x=-2#

Explanation:

Consider #3(x+5)# This means that you have 3 lots of #(x+5)#

Which is: #x+5#
#" "x+5#
#" "ul(x+5) " "larr" add#
#" "3x+15#

#color(green)("Basically you multiply everything inside the brackets by 3")#

So #" "color(brown)(3(x+5)+6=15)" "color(blue)(->" "3x+15+6=15#

#3x+21=15#

'~~~~~~~~~~~~~~~~~~~~~~~~~~

#color(green)("To get rid of the 21 on the left subtract 21 from both sides")#

#3x+21-21=15-21#

#3x+0=-6#
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#color(green)("To get rid of the 3 from "3x" divide both sides by 3")#

#3/3 xx x=-6/3#

But #3/3=1" and "1xx x =x#

#x=-2#