Categories

# [Smart Math] Geometry Problem 6

Here’s and example of a SMART MATH problem for GEOMETRY.

### Problem

Find the equation of a line with slope –4 and passing through the point (4, 5).

1. x + y = 9
2. x + 4y = 11
3. 4x + y = 21
4. 3x + 2y = 10
5. 5x + y = 30

### The Usual Method

Using the point slope form of equation of a straight line, we get:

$\left( y-5 \right)=-4\left( x-4 \right)$

$\therefore y-5=-4x+16$

$\therefore 4x+y=21$

(Ans: 3)

Estimated Time to arrive at the answer = 30 seconds.

### Using Technique

We already know the slope intercept form as y = mx + c.

The slope here is given as –4.

Thus, y = –4x + c or 4x + y = c

Thus, the coefficient of x should be 4.

Only option ‘3’ satisfies this condition and hence it is the answer.

(Ans: 3)

Estimated Time to arrive at the answer = 5 seconds.
[starrater tpl=10]

[contentblock id=smartmath-blockquote]