Question
Find the roots
x1=21−29,x2=21+29
Alternative Form
x1≈−2.192582,x2≈3.192582
Evaluate
x2−x−7
To find the roots of the expression,set the expression equal to 0
x2−x−7=0
Substitute a=1,b=−1 and c=−7 into the quadratic formula x=2a−b±b2−4ac
x=21±(−1)2−4(−7)
Simplify the expression
More Steps

Evaluate
(−1)2−4(−7)
Evaluate the power
1−4(−7)
Multiply the numbers
More Steps

Evaluate
4(−7)
Multiplying or dividing an odd number of negative terms equals a negative
−4×7
Multiply the numbers
−28
1−(−28)
If a negative sign or a subtraction symbol appears outside parentheses, remove the parentheses and change the sign of every term within the parentheses
1+28
Add the numbers
29
x=21±29
Separate the equation into 2 possible cases
x=21+29x=21−29
Solution
x1=21−29,x2=21+29
Alternative Form
x1≈−2.192582,x2≈3.192582
Show Solution
