What do we know about those two lines?

They are perpendicular, meaning they have the same slope.
We know the slope of both is not zero (neither is vertical).
Therefore either
1) Both slopes are positive and therefore the product is positive
2) Both slopes are negative and therefore the product is positive (minus by a minus is a plus)

For the y intercepts, we know that the line P passes through the origin.
Therefore its Y intercept is zero.
[draw it if this is not obvious and ask where does it cross the y axis]
Therefore the Y intercept of line K and line P is zero.
[anything multiplied by a zero is a zero]

So we know that the product of slopes is positive, and we know that the product of Y intercepts is zero.
So the product of slopes must be greater.
Answer A

4 0

3 years ago

When x-y=3 work out the value of y-x

GalinKa [24]

The value of y-x is (-3)

<u>Solution:</u>

Given: The value of x-y=3

To find: The value of y-x

$\bold{x-y=3\rightarrow (1)}$

Let's multiply the equation (1) by (- 1) on both sides,

$\Rightarrow\bold{(x - y)\times(- 1) = 3\times(- 1)}$

$\Rightarrow\bold{-(x-y)=-3}$

On multiplying the sign,

$\Rightarrow\bold{(-x+y)=-3}$

The above equation can also be written as,

$\Rightarrow\bold{y-x=-3\rightarrow \text{(The required equation)}}$

<u>Multiplication of signs:</u>

$\Rightarrow( + )\times( + ) = ( + )$

$\Rightarrow( + )\times( - ) = ( - )$

$\Rightarrow( - )\times( + ) = ( - )$

$\Rightarrow( - )\times( - ) = ( + )$

In simpler terms, when we multiply two integers with the same signs, the result is always positive and when we multiply two integers with different signs, the result is always negative.

5 0

3 years ago