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=9−85,x2=9+85
Alternative Form
x1≈−0.219544,x2≈18.219544
Evaluate
x2−18x−4=0
Substitute a=1,b=−18 and c=−4 into the quadratic formula x=2a−b±b2−4ac
x=218±(−18)2−4(−4)
Simplify the expression
More Steps
Evaluate
(−18)2−4(−4)
Multiply the numbers
More Steps
Evaluate
4(−4)
Multiplying or dividing an odd number of negative terms equals a negative
−4×4
Multiply the numbers
−16
(−18)2−(−16)
Rewrite the expression
182−(−16)
If a negative sign or a subtraction symbol appears outside parentheses, remove the parentheses and change the sign of every term within the parentheses
182+16
Evaluate the power
324+16
Add the numbers
340
x=218±340
Simplify the radical expression
More Steps
Evaluate
340
Write the expression as a product where the root of one of the factors can be evaluated
4×85
Write the number in exponential form with the base of 2
22×85
The root of a product is equal to the product of the roots of each factor
22×85
Reduce the index of the radical and exponent with 2
285
x=218±285
Separate the equation into 2 possible cases
x=218+285x=218−285
Simplify the expression
More Steps
Evaluate
x=218+285
Divide the terms
More Steps
Evaluate
218+285
Rewrite the expression
22(9+85)
Reduce the fraction
9+85
x=9+85
x=9+85x=218−285
Simplify the expression
More Steps
Evaluate
x=218−285
Divide the terms
More Steps
Evaluate
218−285
Rewrite the expression
22(9−85)
Reduce the fraction
9−85
x=9−85
x=9+85x=9−85
Solution
x1=9−85,x2=9+85
Alternative Form
x1≈−0.219544,x2≈18.219544
Show Solution
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