Will somebody confirm or dismiss either the mistake or my misunderstanding

[Probability]

y - ( -2) = -2(x - (-1))

I thought it worked out like this;

y + 2 = -2x + 1

subtract 2 from both sides;

y = -2x - 1

My book says the solution is;

y = -2x - 4

Please advise thanks

Sorry my mistake did not see the arithmetic correctly

y - (-2) = -2x - (-1)

y + 2 = -2x - 2

y = -2x - 4

subtracting 2 to both side = - 4

I hope

 

[pappus]

y - ( -2) = -2(x - (-1))

I thought it worked out like this;

y + 2 = -2x + 1 <--- you didn't expand the brackets correctly

subtract 2 from both sides;
y = -2x - 1
My book says the solution is;
y = -2x - 4
Please advise thanks

Sorry my mistake did not see the arithmetic correctly

y - (-2) = -2x - (-1)

y + 2 = -2x - 2

y = -2x - 4

subtracting 2 to both side = - 4

I hope

Since you know what should come out you've "managed" to get the correct result but ...

• \(\displaystyle \displaystyle{y - ( -2) = -2(x - (-1))}\)
• \(\displaystyle \displaystyle{y +2 = -2(x +1)}\)
• \(\displaystyle \displaystyle{y +2 = -2x -2}\)

Now continue.

 

[Probability]

Since you know what should come out you've "managed" to get the correct result but ...

• \(\displaystyle \displaystyle{y - ( -2) = -2(x - (-1))}\)
• \(\displaystyle \displaystyle{y +2 = -2(x +1)}\)
• \(\displaystyle \displaystyle{y +2 = -2x -2}\)

Now continue.

\(\displaystyle \displaystyle{y+2 - 2 = - 2x - 2 - 2}\)
\(\displaystyle \displaystyle{y = - 2x - 4}\)