Question

I need help with these questions For 21) A:y=x+4 B:y=2x C:2x+2 D:2/3x+1

Answer 1

19.
Option (B) is the correct one.

Explanation:

The equation of line be is ,
y = 2x-4,

we have general equation give by,
y = mx +c

wherr m is the slope of the line and x and y are the coordinates changing,

Comparing these two we get the slop of line B as 2.

A thing you need to know here that product of slopes of a line perpendicular to another is -1.
Using this relation,

The slope of line a will be -1/2.

Let A pass through a coordinate (x,y).

Now,

Slope will be give by,
$\frac{y - 1}{x +2} = - \frac{1}{2} \\ y - 1= - \frac{x}{2} - 1 \\ y = - \frac{x}{2}$

20.
Option (A) is the correct one.

How?:

Equation of line B is y = 3x-1.

Once again using the general equation for a line,
y =mx+c
Slope of B will be 3.

Now for a pair of parallel lines their slopes are equal.

So,
Slope of A must also be 3.

Applying the generation equation for a line on A gives,

y = 3x+c

Since A is passing though coordinates (2,4) the values must satisfy this equation,

So we have,

$4 = 2(3) + c \\ c = 4 - 6 = - 2$
Now that we have value for c.
We can get the the equation we need.
So we have,

y = 3x -2.

Hope it helps.