Maths-
General
Easy

Question

# Given that the coordinate (3, 4) lies on the line y = 3x + c calculate the y-intercept of the straight line.

Hint:

## The correct answer is: the y-intercept is -5.

### Step by step solution:The given equation of the line isy = 3x + cComparing with the slope intercept form of the equation of a line,y = mx + cWe get that  denotes the y intercept of the line in the equation y = 3x + cAs every point that lies on the line satisfies the equation of the line, we get the point (3, 4) satisfies the equation y = 3x + cThus, we have4 = 3 × 3 + cSimplifying, we get4 = 9 + cSubtracting 9 on both sides, we getc = 4 - 9 = -5Thus, the value of c is -5Hence, the y-intercept is -5.

The student needs to remember all the different forms of equation of a line and what each term and notation signifies in the equation.
We can find the slope and y-intercept directly from the general form of the equation too; slope = and y-intercept = , where the general form of equation of a line is ax + by + c = 0.