Shortcut Trick
For any point to lie on a given line, its (x, y) coordinates must satisfy the line's equation.
Substitute the given points into y = −3x + 7 directly:
(0, 7) ⇒ 7 = −3(0) + 7 ⇒ 7 = 7 (True)
(2, 1) ⇒ 1 = −3(2) + 7 ⇒ 1 = 1 (True)
(3, −2) ⇒ −2 = −3(3) + 7 ⇒ −2 = −2 (True)
∴ The correct answer is (0,7), (2,1) and (3,-2) all.
Alternate Method
Given:
Equation of the straight line: y = −3x + 7
Points to verify: (0, 7), (2, 1), and (3, −2)
Formula Used:
A point (x1, y1) lies on the line y = mx + c if substituting x = x1 gives y = y1.
(0, 7)
(2, 1)
(3, -2)
y = -3x + 7
X
Y
O
Calculations:
Let's verify each given point individually by putting the values in the equation y = −3x + 7.
1. Checking Point (0, 7):
⇒ Put x = 0 and y = 7 in the equation.
⇒ LHS = 7
⇒ RHS = −3(0) + 7 = 7
⇒ LHS = RHS, so the point (0, 7) lies on the line.
2. Checking Point (2, 1):
⇒ Put x = 2 and y = 1 in the equation.
⇒ LHS = 1
⇒ RHS = −3(2) + 7 = −6 + 7 = 1
⇒ LHS = RHS, so the point (2, 1) lies on the line.
3. Checking Point (3, −2):
⇒ Put x = 3 and y = −2 in the equation.
⇒ LHS = −2
⇒ RHS = −3(3) + 7 = −9 + 7 = −2
⇒ LHS = RHS, so the point (3, −2) lies on the line.
⇒ Since all three points successfully satisfy the linear equation, they all lie on the same straight line.
∴ The correct answer is (0,7), (2,1) and (3,-2) all.
Additional Information
Equation of a Straight Line (Slope-Intercept Form)
The equation y = mx + c represents a straight line, where 'm' is the slope (gradient) of the line and 'c' is the y-intercept (the point where the line crosses the Y-axis).
Slope of a Line
The slope 'm' of a line passing through any two points (x1, y1) and (x2, y2) is calculated using the formula: m = (y2 − y1) ÷ (x2 − x1).
Collinear Points
Three or more points are said to be collinear if they all lie on the same straight line. The area of a triangle formed by collinear points is always equal to 0.