How do you graph #7x + 8y = 29#?

1 Answer
Jun 10, 2017

Solve for #y#, find the intercepts, draw the intercepts, and connect the dots.

Explanation:

Step 1. Solve the equation for #y# in terms of #x#.

Subtract #7x# from both sides

#7xcolor(red)(-7x)+8y=29color(red)(-7x)#

#8y=29-7x#

Divide both sides by #8#

#(cancel(8)y)/color(red)(cancel(8))=(29-7x)/color(red)(8)#

#y=29/8-7/8x" "# or #" " y=-7/8x+29/8#

Step 2. Solve for important parts of the line.

#y#-intercept: Let #x=0#

#y=-7/8xxcolor(red)(0)+29/8#

#y=0+29/8=29/8~~3.625#

So the #y#-intercept is #(0,3.625)#

#x#-intercept: Let #y=0#

#color(red)(0)=-7/8x+29/8#

Multiply all sides by #8# to get rid of the ugly fractions.

#color(red)(8)xx0=color(red)(8)xx(-7/8)x+color(red)(8)xx(29/8)#

#0=-7x+29#

Add #7x# to both sides

#7x=29#

Divide both sides by #7#

#x=29/7~~4.14#

So the #x#-intercept is #(4.14,0)#

Step 3. Plot these two intercepts and draw a line connecting them

Desmos.com and MS Paint