Question

I tried to solve: 1 - 9d = -8d - 16First, I added 8d to both sides bringing me to 1 - 17d = -16, Then I subtracted 1 on both sides bringing me to -17d = - 17, then I divided by -17 on both sides, bring me to d = 1. I'm confused about where I went wrong in the problem.

Answer 1

Step 1

Given; 1 - 9d = -8d - 16

Find the value of d

Step 2

$\begin{gathered} Add\text{ 8d to both sides} \\ 1-9d+8d=-8d+8d-16 \\ simplify \\ 1-d=-16 \\ subtract\text{ 1 from both sides} \\ 1-1-d=-16-1 \\ -d=-17 \end{gathered}$$\begin{gathered} divide\text{ both sides by -1} \\ \frac{-d}{-1}=\frac{-17}{-1} \\ d=17 \end{gathered}$

The error was from where you added 8d to both sides and simplified

$1-9d+8d=-8d+8d-16$

when you do this

$\begin{gathered} For\text{ }LHS \\ 1-9d+8d=1-d \\ For\text{ RHS} \\ -8d+8d-16=-16 \\ Equating\text{ both sides} \\ 1-d=-16 \\ From\text{ here the solution comes out} \end{gathered}$

Answer;

$d=17$