Question

How would you do number 12 and 15?

Answer 1

`x_1=x_2=-(2)/(3)`

Explanation:

For the quadratic equation
`ax^2+bx+c=0` the discriminant is defined as

`D=b^2-4ac`

and the quadratic formula for the roots gives us two roots:

`x_1=(-b-√(D))/(2a)`

and

`x_2=(-b+√(D))/(2a)`

For the equation
`9x^2 +12x+4=0` use quadratic formula to find roots:

`D=12^2-4\cdot 9\cdot 4=144-144=0`

So,

`x_1=x_2=(-12\pm √(0))/(2\cdot 9)=-(12)/(18)=-(2)/(3)`