Question

*The sum of roots of quadratic equation x² - 9x + 18 = 0 is …….*

1️⃣ -9
2️⃣ 9
3️⃣ -18
4️⃣ 18​

Answer 1

• x² - 9x + 18 = 0
• here : a = 1 , b = -9 , c = 18
• Sum of roots = α+β = -b/a = -(-9)/1 = 9
• Sum of Roots = 9
• Option 2⃣ → 9 is correct

Answer 2

The sum of roots of quadratic equation is 6+3=9

Step-by-step explanation:

In the given question, we need to find the sum of roots of quadratic equation x²-9x+18=0

This can be done in two methods.

METHOD-1: To find out the roots of the equation.

⇒x²-9x+18=0

⇒x²-6x-3x+18=0

⇒x(x-6)-3(x-6)=0

⇒(x-3)(x-6)=0

⇒x=3,6

⇒ The roots of the equation are 3 and 6

⇒ The sum of the roots = 3+6=9

Hence the sum of the roots=9

METHOD-2: To use the formula for sum of roots of the quadratic equation.

We have, the formula for sum of roots = -b/a

where b is coefficient of x and a is the coefficient of x².

⇒b= -9 and a=1

⇒ -b/a = -(-9)/1

⇒Sum of roots is equals to 9

Hence from both the methods we found that the sum of roots of quadratic equation x²-9x+18=0 is 9

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