Which of following equation has 4 as a root?
- $\displaystyle { x }^{ 2 }-4x+5=0$
- $\displaystyle { x }^{ 2 }-9x+20=0$
- $\displaystyle 2{ x }^{ 2 }-7x+6=0$
- $\displaystyle 3{ x }^{ 2 }-6x-2=0$
Reveal answer
Fill a bubble to check yourself
B
Correct answer
Explanation
Substitute x = 4 into the equations. For B: 4^2 - 9(4) + 20 = 16 - 36 + 20 = 0. This confirms 4 is a root.
AI explanation
To check if 4 is a root of an equation, we substitute x = 4 into the given options and look for a result of zero. For the equation x^2 - 9x + 20 = 0, substituting the value gives 4^2 - 9(4) + 20 = 16 - 36 + 20. Since this calculates to 0, the equation has 4 as a root.