Algebra
Calculus
Trigonometry
Matrix
Question
Solve the quadratic equation
Solve using the quadratic formula
Solve by completing the square
Solve using the PQ formula
x1=2−22,x2=2+22
Alternative Form
x1≈−2.690416,x2≈6.690416
Evaluate
x2−4x−18=0
Substitute a=1,b=−4 and c=−18 into the quadratic formula x=2a−b±b2−4ac
x=24±(−4)2−4(−18)
Simplify the expression
More Steps
Evaluate
(−4)2−4(−18)
Multiply the numbers
More Steps
Evaluate
4(−18)
Multiplying or dividing an odd number of negative terms equals a negative
−4×18
Multiply the numbers
−72
(−4)2−(−72)
Rewrite the expression
42−(−72)
If a negative sign or a subtraction symbol appears outside parentheses, remove the parentheses and change the sign of every term within the parentheses
42+72
Evaluate the power
16+72
Add the numbers
88
x=24±88
Simplify the radical expression
More Steps
Evaluate
88
Write the expression as a product where the root of one of the factors can be evaluated
4×22
Write the number in exponential form with the base of 2
22×22
The root of a product is equal to the product of the roots of each factor
22×22
Reduce the index of the radical and exponent with 2
222
x=24±222
Separate the equation into 2 possible cases
x=24+222x=24−222
Simplify the expression
More Steps
Evaluate
x=24+222
Divide the terms
More Steps
Evaluate
24+222
Rewrite the expression
22(2+22)
Reduce the fraction
2+22
x=2+22
x=2+22x=24−222
Simplify the expression
More Steps
Evaluate
x=24−222
Divide the terms
More Steps
Evaluate
24−222
Rewrite the expression
22(2−22)
Reduce the fraction
2−22
x=2−22
x=2+22x=2−22
Solution
x1=2−22,x2=2+22
Alternative Form
x1≈−2.690416,x2≈6.690416
Show Solution
Graph
