Question

8. (03.07 MO)Solve x2 - 10x = -21. O x = 7 and x = 3O x = -7 and x = 3O x = -7 andx = -3O x = 7 and x = -3

Answer 1

Given:

Quadratic equation

`x^2-10x+21=0`

To find:

Values of x satisfying given equation.

Step-by-step explanation:

Roots of equation of type

`ax^2-bx+c=0`

roots will be (x-a)(x-b) and x = a,b.

Solution:

We will factorize equation as:

`\begin{gathered} x^2-10x+21=0 \\ x^2-7x-3x+21=0 \\ (x-3)(x-7)=0 \\ x=3,\text{ 7} \end{gathered}`

Hence, 3 and 7 are values of x.