Question

find the equation of the line that has x-intercept -3 and which is perpendicular to the line x-7y+5=0
ans given is y+7x=21​

Answer 1

Answer:

7x+y=21

Step-by-step explanation:

let the eqn of line is

x/a+y/b=1

it has x-intercept= -3, so a=-3

so eqn becomes

x/-3+y/b=1

-bx+3y=b

y=bx/3+b/3------(1)

its slope m1=b/3

The given line is

x-7y+5=0---------(2)

its slope m2=-(1/-7)=1/7

line (1) and (2) are perpendicular

so m1m2=-1

so b/3*(1/7)=-1

b=-21

Putting the value of b in (1)

The eqn is : y=-21x/3-21

y=-7x-21

7x+y=21