Try inserting values for x.
Firstly, estimate a value that you think might result in the given answer of 89, we'll try 5 first.
Therefore, we have 3(5)²+4(5)-2, which is equal to 93.
Obviously, 93 is above the given answer of 89, so we now need to try a lower value. Let's try 4.
Therefore, we have 3(4)²+4(4)-2, which is equal to 62.
Obviously, 62 is below the given answer of 89, so we should try a new value that is the mid-point of the previous values we have tried, in this case 4 and 5. So we'll try the value of 4.5.
You should repeat this process until you get an answer that is within one decimal place of 89 (e.g. 89.3, 88.9 etc).
As long as your final result is equivalent to 88.5≤x≤89.5, you have solved the question.
