Homework Help

What is the point of contact of y = 3x + 4 and 8x - 4y = 16

user profile pic

theta123 | Student, Kindergarten | (Level 1) Salutatorian

Posted September 23, 2013 at 2:51 AM via web

dislike 0 like

What is the point of contact of y = 3x + 4 and 8x - 4y = 16

2 Answers | Add Yours

user profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted September 23, 2013 at 2:54 AM (Answer #1)

dislike 0 like

The co-ordinates of the point at which the lines y = 3x + 4 and 8x - 4y = 16 intersect satisfies both the equations.

Substituting y = 3x + 4 in 8x - 4y = 16

=> 8x - 4(3x + 4) = 16

=> 8x - 12x - 16 = 16

=> -4x = 32

=> x = -8

y = -20

The point of intersection of the lines is (-8, -20)

user profile pic

tonys538 | TA , Undergraduate | (Level 1) Valedictorian

Posted November 28, 2014 at 4:40 PM (Answer #2)

dislike 0 like

To determine the point of contact of the lines y = 3x + 4 and 8x - 4y = 16 solve the system of equations formed by the equations of the lines.

y = 3x + 4...(1)

8x - 4y = 16 ...(2)

4*(1) + (2)

4y + 8x - 4y = 12x + 16 + 16

8x = 12x + 32

-4x = 32

x = -8

Substituting x = -8 in y = 3x + 4 gives y = -8*3 + 4 = -24 + 4 = -20

The point of intersection of the lines is (-8. -20)

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes