Question

Write an equation of the line that passes through the point (4,5) and has a slope of -2.

Answer 1

Explanation:

slope=-2

now using slope intercet formof equation of straight line,we get

y=mx+b

or, y=-2x + b

y + 2x =b

2x + y=b ...................... eq(i)

since the line passes through the point (4,5) it satisfies the equation (i)

y=5 and x=4 so,

equation is 2x +y =b

2*4 + 5=b

8+5=b

13=b

substituting the value of b in eq(i)

2x + y=b

2x + y=13

2x + y-13=0 is the required equation of the line.

Answer 2

y = - 2x + 13

Explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Here m = - 2 , then

y = - 2x + c ← is the partial equation

To find c substitute (4, 5) into the partial equation

5 = - 8 + c ⇒ c = 5 + 8 = 13

y = - 2x + 13 ← equation of line