what this student did was distribute the x to all 3 numbers when what they should have done was just combine 7x and -2x, and the answer should be 5x +8
Step-by-step explanation:
By the student placing x on the outside they are making the equation seem as if 8 also had an x. However if we look at the original problem 8 does not have any variable so right away that was their first mistake. Instead they had to find the numbers that had similar values. In this case it is negative 2x and 7x. We combine those two to get 5x+8 we cannot combine these two because as said previously 8 doesnt have a variable. so the answer stays with the expression 5x+8
