Question

can anyone please double check my work? the math problem is ..write an equation of the line containing the given point and perpendicular to the given line.....
(0,9);2x+7y...I got the answer of -2/9x+9

Answer 1

a perp.line has the propety that the slope of the lines, when multiplied together will be (-1)

Answer 2

y=-2/7x +....

perp line:

y = 7/2x + b (x=0,y=9)

9 = 7/2(0) + b

b=9

perp line:

y = 7/2x + 9 {9 = 18/2}

-7x + 2y = 18 ; some texts dont like the (-) in front so multiply everything by (-1)

7x - 2y = -18

Answer 3

(-2/7)(7/2) = -1

Answer 4

think of the slope as:

-(first)/(last) which in this case is:

-(2)/(7); now we need to multiply this by some number to get (-1)

-(2/7)n = -1
-2n = -7

n = -7/-2 ; since 2negatives give a positive we write:

n = 7/2 for the slope of the perp.line...