Mathematics

Grade-8

Easy

Question

# 1) Points M(2, 9) and N(–1, 3) are on a line with y-intercept –4. What is the equation of the line?

- y = –4x – 2
- y = –2x + 4
- y = 2x – 4
- y = 4x + 2

Hint:

Mathematics

Grade-8

Easy

Question

- y = –4x – 2
- y = –2x + 4
- y = 2x – 4
- y = 4x + 2

Hint:

2. Equation of a line, when its slope and intercept is given can be given as- y = mx + b, where m = slope and b = y-intercept.

Points on the line- M(2, 9) and N(–1, 3)

y-intercept = b = -4

TO FIND-

Equation of the given line.

SOLUTION-

We are given that M(2, 9) and N(–1, 3) are on the given line.

Hence, x1 = 2, y1 = 9, x2 = -1 and y2 = 3

Slope = m = y2-y1 / x2-x1

∴ Slope = m = (3 - 9) / (-1 - 2)

∴ Slope = m = -6 / -3

∴ Slope = m = 2 ................................. (Equation i)

Substituting values in y = mx + b, we get-

y = 2x + (-4) ....................................... (From given information & Equation i)

∴ y = 2x - 4

FINAL ANSWER-

Option 'c' i.e. 'y = 2x – 4' is the correct answer to the given question.