Question
Factor the expression
(x−1)(x+1)(x2+4)
Evaluate
x4+3x2−4
Rewrite the expression
x4+(4−1)x2−4
Calculate
x4+4x2−x2−4
Rewrite the expression
x2×x2+x2×4−x2−4
Factor out x2 from the expression
x2(x2+4)−x2−4
Factor out −1 from the expression
x2(x2+4)−(x2+4)
Factor out x2+4 from the expression
(x2−1)(x2+4)
Solution
(x−1)(x+1)(x2+4)
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Find the roots
x1=−2i,x2=2i,x3=−1,x4=1
Evaluate
x4+3x2−4
To find the roots of the expression,set the expression equal to 0
x4+3x2−4=0
Factor the expression
(x−1)(x+1)(x2+4)=0
Separate the equation into 3 possible cases
x−1=0x+1=0x2+4=0
Solve the equation
More Steps

Evaluate
x−1=0
Move the constant to the right-hand side and change its sign
x=0+1
Removing 0 doesn't change the value,so remove it from the expression
x=1
x=1x+1=0x2+4=0
Solve the equation
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Evaluate
x+1=0
Move the constant to the right-hand side and change its sign
x=0−1
Removing 0 doesn't change the value,so remove it from the expression
x=−1
x=1x=−1x2+4=0
Solve the equation
More Steps

Evaluate
x2+4=0
Move the constant to the right-hand side and change its sign
x2=0−4
Removing 0 doesn't change the value,so remove it from the expression
x2=−4
Take the root of both sides of the equation and remember to use both positive and negative roots
x=±−4
Simplify the expression
More Steps

Evaluate
−4
Evaluate the power
4×−1
Evaluate the power
4×i
Evaluate the square root
2i
x=±2i
Separate the equation into 2 possible cases
x=2ix=−2i
x=1x=−1x=2ix=−2i
Solution
x1=−2i,x2=2i,x3=−1,x4=1
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