Question

How do you solve `x^2 - 10x + 21= 0` graphically?

Answer 1

The graph is given below

Explanation:

Here it is graph{(x^2)-(10x)+21 [-3.705, 16.295, -5.055, 4.945]}

Note that at `x=5` you see it is the minimum

Answer 2

`x=3" or " x=7`

Explanation:

`"from the graph of " x^2-10x+21`
graph{x^2-10x+21 [-10, 10, -5, 5]}

`"the solution to "`

`x^2-10x+21=0" are the values of x where the"`
`"graph crosses the x-axis"`

`rArrx=3" or " x=7`

`color(blue)"As a check"`

`"Substitute these values into " x^2-10x+21`

`x=3to9-30+21=0larrcolor(red)" True"`

`x=7to49-70+21=0larrcolor(red)"True"`