Question
Factor the expression
2(x2−x−1)
Evaluate
2x2−2x−2
Solution
2(x2−x−1)
Show Solution

Find the roots
x1=21−5,x2=21+5
Alternative Form
x1≈−0.618034,x2≈1.618034
Evaluate
2x2−2x−2
To find the roots of the expression,set the expression equal to 0
2x2−2x−2=0
Substitute a=2,b=−2 and c=−2 into the quadratic formula x=2a−b±b2−4ac
x=2×22±(−2)2−4×2(−2)
Simplify the expression
x=42±(−2)2−4×2(−2)
Simplify the expression
More Steps

Evaluate
(−2)2−4×2(−2)
Multiply
More Steps

Multiply the terms
4×2(−2)
Rewrite the expression
−4×2×2
Multiply the terms
−16
(−2)2−(−16)
Rewrite the expression
22−(−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
22+16
Evaluate the power
4+16
Add the numbers
20
x=42±20
Simplify the radical expression
More Steps

Evaluate
20
Write the expression as a product where the root of one of the factors can be evaluated
4×5
Write the number in exponential form with the base of 2
22×5
The root of a product is equal to the product of the roots of each factor
22×5
Reduce the index of the radical and exponent with 2
25
x=42±25
Separate the equation into 2 possible cases
x=42+25x=42−25
Simplify the expression
More Steps

Evaluate
x=42+25
Divide the terms
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Evaluate
42+25
Rewrite the expression
42(1+5)
Cancel out the common factor 2
21+5
x=21+5
x=21+5x=42−25
Simplify the expression
More Steps

Evaluate
x=42−25
Divide the terms
More Steps

Evaluate
42−25
Rewrite the expression
42(1−5)
Cancel out the common factor 2
21−5
x=21−5
x=21+5x=21−5
Solution
x1=21−5,x2=21+5
Alternative Form
x1≈−0.618034,x2≈1.618034
Show Solution
