x^2 - 10x + 21 = 0
- First, factorise the quadratic equation.
- Find two numbers that multiply to give 21 and add to give 10. 7 and 3
- (x-7)(x-3)=0
- Now find the value x so that when these brackets are multiplied together the answer is 0.
- So either x=7 or x=3
- You can check the answer by substituting 7 and 3 into the equation.
