Question

lan solved the below problem He is confident his work is correct Checklar's work If he is correct, explain the work that he did. If he has made a mistake, idenufy his mistake and explain to lan host fint​

Answer 1

See below.

Explanation:

The mistake Ian made was incorrectly distributing -(-91). When multiplying two negative numbers the result is always positive:
`-a \cdot -b=-a(-b)=ab`.

This error meant he added 91 to both sides of the equation in Step 3 of his calculation, when he should subtract 91 from both sides.

Therefore, the correct calculation is:

`\begin{array} { r l}511 & = -7(10x-13)\\\\511 & = -70x \phantom{)))}+91\\\\-91 & \phantom{))))))))))))} -91\\\\\cline{1-2}\\420 & = -70x\\\\(420)/(-70) & = (-70x)/(-70)\\\\-6 & = x\end{array}`

Answer 2

Correct steps given below:

• 511 = -7 (10x - 13)
• 511 = - 70x - (-91)
• 511 = -70x + 91
• -91 - 91
• ---------------------
• 420 = -70x
• 420/-70 = -70x/-70
• -6 = x

Ian missed the step 3 above.

He wrongly added 91 to both sides instead of subtracting, this resulted in wrong solution.