With number choices and an equation set equal to zero, substitution can be faster than solving the whole quadratic. Put a candidate into the left side in Desmos and compare the result with zero. A solution makes the left side equal the right side. A number that appears in the equation is not automatically a solution.
Hints
- Hint 1
A solution is a value of that makes an equation true. The right side is , so what must the left side become when you put in a choice?
- Hint 2
You need only one choice that works. Substitute a candidate for every on the left side; if Desmos shows anything other than , try another candidate.
Step-by-step
Test a choice by substitution
Step 1Check whether the constant is a solution
The might make look promising, but a solution must make the left side equal . Type in Desmos. It shows , so does not work.
- Step 2
Find a choice that makes zero
Try next. Type in Desmos; it shows . That matches the right side, so is a solution. Choice B.