Consider this quadratic equation. x2 + 2x + 7 = 21

The number of positive solutions to this equation is
.

The approximate value of the greatest solution to the equation, rounded to the nearest hundredth, is
.

There is one positive solution (x=2.87)

The approximate value of the greatest solution is 2.87

To do a quadratic equation you have the quadratic formula of: ( -b+/- sqrt b^2-4ac)/2a

In order to use it, you need your equation to equal zero so subtract 21 from both sides:

x2+2x-14

Now you can define a, b, and c

a=1, b=2, c=-14

Now plug them into the equation!

-(2)+ sqrt (2)^2-4(1)(-14)/ 2(1) = 2.87298

Make sure to do subtraction as well! ( plus OR minus)

-2- sqrt 2(2)^2-4(1)(-14)/2(1) = -4.87298

You can double check the answers by plugging them back into the original equation :)

Looks like there’s only one POSITIVE solution, x=2.87

This is also the greatest solution, so x=2.87 :D