Line [tex]$QR$[/tex] goes through points [tex]$Q(0,1)$[/tex] and [tex]$R(2,7)$[/tex]. Which equation represents line [tex]$QR$[/tex]?

A. [tex]$y - 1 = 6x$[/tex]
B. [tex]$y - 1 = 3x$[/tex]
C. [tex]$y - 7 = 2x - 6$[/tex]
D. [tex]$y - 7 = x - 2$[/tex]



Answer :

To determine the equation of the line QR, we first need to find the slope of the line that passes through points [tex]\( Q(0, 1) \)[/tex] and [tex]\( R(2, 7) \)[/tex].

### Step 1: Calculate the Slope
The formula for the slope [tex]\( m \)[/tex] between two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is given by:

[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

Substituting in our points [tex]\( Q(0, 1) \)[/tex] and [tex]\( R(2, 7) \)[/tex]:

[tex]\[ m = \frac{7 - 1}{2 - 0} = \frac{6}{2} = 3 \][/tex]

So, the slope of the line QR is 3.

### Step 2: Use the Point-Slope Form
Next, we'll use the point-slope form of the equation of a line, which is:

[tex]\[ y - y_1 = m(x - x_1) \][/tex]

We can use point [tex]\( Q(0, 1) \)[/tex] as [tex]\( (x_1, y_1) \)[/tex] and our calculated slope [tex]\( m = 3 \)[/tex]:

[tex]\[ y - 1 = 3(x - 0) \][/tex]

Simplifying this equation:

[tex]\[ y - 1 = 3x \][/tex]

### Conclusion
The equation of the line QR in point-slope form is:

[tex]\[ y - 1 = 3x \][/tex]

Comparing this with the provided options, we see that the correct answer is:

[tex]\[ y - 1 = 3x \][/tex]

Therefore, the equation that represents line QR is:

[tex]\[ \boxed{y - 1 = 3x} \][/tex]