x2+4x-21=0
Consider the form x2+bx+c. Find a pair of integers whose product is c and whose sum is b. In this case, whose product is -21 and whose sum is 4.
-3,7
Write the factored form using these integers.
(x-3)(x+7)=0
(x-3)(x+7)=0
If any individual factor on the left side of the equation is equal to 0, the entire expression will be equal to 0.
x-3=0
x+7=0
Set the first factor equal to 0.
x-3=0
Add 3 to both sides of the equation.
x=3
x=3
Set the next factor equal to 0.
x+7=0
Subtract 7 from both sides of the equation.
x=-7
x=-7
The final solution is all the values that make (x-3)(x+7)=0 true.
x=3,-7
Solve Using the Square Root Property x^2+4x-21=0
