# SOLVEDFind the equation of the line joining (0-3), (-5,0)

#### FailInMaths

Question: Find the equation of the line joining $$\displaystyle (0-3)$$, $$\displaystyle (-5,0)$$

I encountered a problem when finding the gradient. y2-y1/x2-x1

If $$\displaystyle (0, -3)$$ is the x1,y1

$$\displaystyle 0-(-3)/-5-0$$ = $$\displaystyle 3/-5$$ = $$\displaystyle -0.6$$

If $$\displaystyle (0, -3)$$ is the x2,y2

$$\displaystyle -3-0/0-5$$ = $$\displaystyle -3/-5$$ = $$\displaystyle 0.6$$

Where am I wrong? [Solved]

My workings for this question:

$$\displaystyle =$$ $$\displaystyle (-3-0)/(0-(-5)$$
$$\displaystyle =$$ $$\displaystyle -3/5$$
$$\displaystyle =$$$$\displaystyle -0.6$$
$$\displaystyle 0=-0.6(-5)+b$$
$$\displaystyle 0=3+b$$
$$\displaystyle 0-3=3-3+b$$
$$\displaystyle -3=b$$
Therefore, $$\displaystyle y=-0.6x-3$$

Last edited:

#### masters

MHF Helper
Question: Find the equation of the line joining $$\displaystyle (0-3)$$, $$\displaystyle (-5,0)$$

I encountered a problem when finding the gradient. y2-y1/x2-x1

If $$\displaystyle (0, -3)$$ is the x1,y1

$$\displaystyle 0-(-3)/-5-0$$ = $$\displaystyle 3/-5$$ = $$\displaystyle -0.6$$

If $$\displaystyle (0, -3)$$ is the x2,y2

$$\displaystyle -3-0/0-5$$ = $$\displaystyle -3/-5$$ = $$\displaystyle 0.6$$

Where am I wrong?
Hi FailInMaths,

You just made one small error. It should be:

$$\displaystyle \frac{-3-0}{0-(-5)}=\frac{-3}{5}=-0.6$$

FailInMaths

#### FailInMaths

Hi FailInMaths,

You just made one small error. It should be:

$$\displaystyle \frac{-3-0}{0-(-5)}=\frac{-3}{5}=-0.6$$
Oh yeah! I will try to solve this problem now

Thanks

#### FailInMaths

Can someone check it for me?

Thanks

#### masters

MHF Helper

Can someone check it for me?

Thanks
Your answer is indeed correct, but you went to lot of trouble to get there.

You found the slope to be -.6

One of your given points was the y-intercept (0, -3).

Simple substitution into y = mx + b would suffice.

$$\displaystyle y = -.6x - 3$$

FailInMaths

#### FailInMaths

Oh,yeah thanks for point out that and thanks for checking my answer

#### masters

MHF Helper
Oh,yeah thanks for point out that and thanks for checking my answer
You're welcome!!