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Question

find the equation for the line that passes through the point (4,-9) and is parallel to the line 4x-8y=7

Answer 1

The equation 4x-8y=7  is in Standard Form Ax+By=C).  The slope is (-A/B).  All parallel lines have the same slope, so their equations look like:    4x-7y=C   and we need a point to find C.  Use (4,-9).

 

    4(4)-8(-9) = C

     16 +72 = C

        56 = C

 

The equation of the parallel line, in Standard Format, is:     4x -8y = 56  or, reduced,   x-2y = 14

The equation of the parallel line, in slope-intercept form, is:   y = x/2 - 7

Answer 2

This is a calculus question?

4x - 8y = 7

-8y = -4x + 7

y = x/2 + 7/8

Line parallel

y = x/2 + b

-9 = 4/2 + b

-9 = -2 + b

-7 = b

y = x/2 - 7