Question 775107
Thanks for posting the problem correctly!
{{{x^2-3x=10}}} 
{{{x^2-3x=10}}} first subtract 10 from each side of the equal sign
{{{x^2-3x-10=0}}} next pretend instead of 0 on the right side you have y
{{{x^2-3x-10=y}}} plug in a few values for x (any values) and evaluate, this will give you the matching y's. Here's the table
x | y
________
0 | -10
-2|  0
5 | 0 
feel free to do more points, you need quite a few to graph a quadratic but you get the point.
Now plot these points
{{{ graph( 300, 200, -10, 10, -10, 10, x^2-3x-10) }}}
As you can see from the graph it crosses x axis at 5 and -2
Now to check the results plug in the solution one at a time
check for x=5
{{{x^2-3x=10}}} 
{{{5^2-3*5=10}}} 
{{{25-15=10}}} 
{{{10=10}}} left side equals right side so x=5 is a solution
check for x=-2
{{{(-2)^2-3(-2)=10}}} 
{{{4+6=10}}} 
{{{10=10}}} left side equals right side so x=-2 is a solution