Question

Orla says that x = 5 is a solution of x² + 3x - 10 = 0 and Fiona says that x = -5 is

a solution of x² + 3x -10=0.

One of the answers is correct. Say which answer is correct and justify your answer

Answer 1

Fiona is correct

Explanation:

Substitute x = 5 and x = - 5 into the left side of the equation and if equal to the right side then it is a solution of the equation.

x = 5 : 5² + 3(5) - 10 = 25 + 15 - 10 = 30 ≠ 0 ← not a solution

x = - 5 : ( - 5)² + 3(- 5) - 10 = 25 - 15 - 10 = 0 ← correct

Then Fiona is correct with x = - 5 being the solution