Question

Find the product of the slopes $m_1$ and $m_2$ of the straight lines $y=3x-2$ and $x+3y+5=0$.

• A. 0
• B. 1
• C. -1
• D. -2

Answer 1

The correct option is C -1

In the equation $y=3x-2$ the slope will be 3 because it is in the form of $y=mx+c$.

In the equation $x+3y+5=0$, let's take the y-term to one side and rest of the terms to other side.
$⟹3y=-x-5⟹y=-\frac{1}{3}x-\frac{5}{3}$
So, the slope here is $\frac{-1}{3}$.

Now, we calculate the multiplication $m_1\cdot m_2=3\cdot (-\frac{1}{3})$

$m_1\cdot m_2=-1$