) Find the equation of the line passing through the intersection of the lines
3x + 2y = 7 and x – y + 1 = 0 and parallel to 2x + y = 0.
Answers
EXPLANATION.
Equation of lines passing through point of intersection.
⇒ 3x + 2y = 7. - - - - - (1).
⇒ x - y + 1 = 0. - - - - - (2).
Parallel to the line 2x + y = 0.
As we know that,
Solving equation (1) and (2), we get.
We can write equation (2) as,
⇒ x + 1 = y. - - - - - (2).
Put the value of equation (2) in equation (1), we get.
⇒ 3x + 2(x + 1) = 7.
⇒ 3x + 2x + 2 = 7.
⇒ 5x = 7 - 2.
⇒ 5x = 5.
⇒ x = 1.
Put the value of x = 1 in equation (2), we get.
⇒ y = x + 1.
⇒ y = 1 + 1.
⇒ y = 2
Values of (x, y) = (1, 2).
As we know that,
Slope of a parallel line : m = - a/b.
Slope of line : 2x + y = 0 ⇒ m = - 2.
As we know that,
Formula of equation of line.
⇒ (y - y₁) = m(x - x₁).
Put the values in the equation, we get.
⇒ (y - 2) = - 2(x - 1).
⇒ y - 2 = - 2x + 2.
⇒ y + 2x = 2 + 2.
⇒ 2x + y = 4.
Equation of line : 2x + y = 4.