How do you find the x and y intercept of #7x + 3y = –21#?

1 Answer
Feb 25, 2017

Answer:

See the entire solution process below:

Explanation:

To find the #x# intercept by substitution you substitute #0# for #y# and solve for #x#:

#7x + 3y = -21# becomes:

#7x + (3 xx 0) = -21#

#7x + 0 = -21#

#7x = -21#

#(7x)/color(red)(7) = -21/color(red)(7)#

#(color(red)(cancel(color(black)(7)))x)/cancel(color(red)(7)) = -3#

#x = -3# so the x-intercept is #-3# or #(-3, 0)#

To find the #y# intercept by substitution you substitute #0# for #x# and solve for #y#:

#7x + 3y = -21# becomes:

#(7 xx 0) + 3y = -21#

#0 + 3y = -21#

#3y = -21#

#(3y)/color(red)(3) = -21/color(red)(3)#

#(color(red)(cancel(color(black)(3)))y)/cancel(color(red)(3)) = -7#

#y = -7# so the y-intercept is #-7# or #(0, -7)#