Question
Simplify the expression
−2x2−3−84x4
Evaluate
3x2−3−7x2×12x2−5x2
Multiply
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Multiply the terms
−7x2×12x2
Multiply the terms
−84x2×x2
Multiply the terms with the same base by adding their exponents
−84x2+2
Add the numbers
−84x4
3x2−3−84x4−5x2
Solution
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Evaluate
3x2−5x2
Collect like terms by calculating the sum or difference of their coefficients
(3−5)x2
Subtract the numbers
−2x2
−2x2−3−84x4
Show Solution

Find the roots
x∈/R
Evaluate
3x2−3−7x2×12x2−5x2
To find the roots of the expression,set the expression equal to 0
3x2−3−7x2×12x2−5x2=0
Multiply
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Multiply the terms
7x2×12x2
Multiply the terms
84x2×x2
Multiply the terms with the same base by adding their exponents
84x2+2
Add the numbers
84x4
3x2−3−84x4−5x2=0
Subtract the terms
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Simplify
3x2−3−84x4−5x2
Subtract the terms
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Evaluate
3x2−5x2
Collect like terms by calculating the sum or difference of their coefficients
(3−5)x2
Subtract the numbers
−2x2
−2x2−3−84x4
−2x2−3−84x4=0
Solve the equation using substitution t=x2
−2t−3−84t2=0
Rewrite in standard form
−84t2−2t−3=0
Multiply both sides
84t2+2t+3=0
Substitute a=84,b=2 and c=3 into the quadratic formula t=2a−b±b2−4ac
t=2×84−2±22−4×84×3
Simplify the expression
t=168−2±22−4×84×3
Simplify the expression
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Evaluate
22−4×84×3
Multiply the terms
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Multiply the terms
4×84×3
Multiply the terms
336×3
Multiply the numbers
1008
22−1008
Evaluate the power
4−1008
Subtract the numbers
−1004
t=168−2±−1004
Simplify the radical expression
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Evaluate
−1004
Evaluate the power
1004×−1
Evaluate the power
1004×i
Evaluate the power
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Evaluate
1004
Write the expression as a product where the root of one of the factors can be evaluated
4×251
Write the number in exponential form with the base of 2
22×251
The root of a product is equal to the product of the roots of each factor
22×251
Reduce the index of the radical and exponent with 2
2251
2251×i
t=168−2±2251×i
Separate the equation into 2 possible cases
t=168−2+2251×it=168−2−2251×i
Simplify the expression
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Evaluate
t=168−2+2251×i
Divide the terms
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Evaluate
168−2+2251×i
Rewrite the expression
1682(−1+251×i)
Cancel out the common factor 2
84−1+251×i
Use b−a=−ba=−ba to rewrite the fraction
−841−251×i
Simplify
−841+84251i
t=−841+84251i
t=−841+84251it=168−2−2251×i
Simplify the expression
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Evaluate
t=168−2−2251×i
Divide the terms
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Evaluate
168−2−2251×i
Rewrite the expression
1682(−1−251×i)
Cancel out the common factor 2
84−1−251×i
Use b−a=−ba=−ba to rewrite the fraction
−841+251×i
Simplify
−841−84251i
t=−841−84251i
t=−841+84251it=−841−84251i
Substitute back
x2=−841+84251ix2=−841−84251i
Solve the equation for x
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Substitute back
x2=−841+84251i
Simplify
x=−841+84251i
Rewrite the complex number in polar form
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Evaluate
−841+84251i
Determine the modulus and the argument of the complex number
r=(−841)2+(84251)2θ=arctan−84184251
Calculate
r=147θ=arctan−84184251
Since −841+84251i lies in the II quadrant, add π to get the argument in the II quadrant
r=147θ=arctan−84184251+π
Simplify
r=147θ=arctan(−251)+π
Substitute the given values into the formula r(cosθ+isinθ)
147(cos(arctan(−251)+π)+isin(arctan(−251)+π))
x=147(cos(arctan(−251)+π)+isin(arctan(−251)+π))
Calculate the nth roots of a complex r(cos(θ)+i×sin(θ),using nz=nr(cosnθ+2kπ+isinnθ+2kπ)
x=147×cos2arctan(−251)+π+2kπ+isin2arctan(−251)+π+2kπ
Simplify
x=1441372cos2arctan(−251)+π+2kπ+isin2arctan(−251)+π+2kπ
Since n=2,substitute k=0,1 into the expression
x1=1441372cos2arctan(−251)+π+2×0×π+isin2arctan(−251)+π+2×0×πx2=1441372cos2arctan(−251)+π+2×1×π+isin2arctan(−251)+π+2×1×π
Calculate
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Evaluate
2arctan(−251)+π+2×0×π
Any expression multiplied by 0 equals 0
2arctan(−251)+π+0
Removing 0 doesn't change the value,so remove it from the expression
2arctan(−251)+π
x1=1441372cos2arctan(−251)+π+isin2arctan(−251)+πx2=1441372cos2arctan(−251)+π+2×1×π+isin2arctan(−251)+π+2×1×π
Calculate
x1=1441372cos2arctan(−251)+π+isin2arctan(−251)+πx2=1441372cos2arctan(−251)+π+2π+isin2arctan(−251)+π+2π
Calculate
x1=1441372×cos(2arctan(−251)+π)+1441372×sin(2arctan(−251)+π)ix2=1441372×cos(2arctan(−251)+π+2π)+1441372×sin(2arctan(−251)+π+2π)i
x1=1441372×cos(2arctan(−251)+π)+1441372×sin(2arctan(−251)+π)ix2=1441372×cos(2arctan(−251)+π+2π)+1441372×sin(2arctan(−251)+π+2π)ix2=−841−84251i
Solve the equation for x
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Substitute back
x2=−841−84251i
Simplify
x=−841−84251i
Rewrite the complex number in polar form
More Steps

Evaluate
−841−84251i
Determine the modulus and the argument of the complex number
r=(−841)2+(−84251)2θ=arctan−841−84251
Calculate
r=147θ=arctan−841−84251
Since −841−84251i lies in the III quadrant, add π to get the argument in the III quadrant
r=147θ=arctan84184251+π
Simplify
r=147θ=arctan(251)+π
Substitute the given values into the formula r(cosθ+isinθ)
147(cos(arctan(251)+π)+isin(arctan(251)+π))
x=147(cos(arctan(251)+π)+isin(arctan(251)+π))
Calculate the nth roots of a complex r(cos(θ)+i×sin(θ),using nz=nr(cosnθ+2kπ+isinnθ+2kπ)
x=147×cos2arctan(251)+π+2kπ+isin2arctan(251)+π+2kπ
Simplify
x=1441372cos2arctan(251)+π+2kπ+isin2arctan(251)+π+2kπ
Since n=2,substitute k=0,1 into the expression
x1=1441372cos2arctan(251)+π+2×0×π+isin2arctan(251)+π+2×0×πx2=1441372cos2arctan(251)+π+2×1×π+isin2arctan(251)+π+2×1×π
Calculate
More Steps

Evaluate
2arctan(251)+π+2×0×π
Any expression multiplied by 0 equals 0
2arctan(251)+π+0
Removing 0 doesn't change the value,so remove it from the expression
2arctan(251)+π
x1=1441372cos2arctan(251)+π+isin2arctan(251)+πx2=1441372cos2arctan(251)+π+2×1×π+isin2arctan(251)+π+2×1×π
Calculate
x1=1441372cos2arctan(251)+π+isin2arctan(251)+πx2=1441372cos2arctan(251)+π+2π+isin2arctan(251)+π+2π
Calculate
x1=−1441372×cos(2π−arctan(251))+1441372×sin(2arctan(251)+π)ix2=1441372×cos(2arctan(251)+π+2π)+1441372×sin(2arctan(251)+π+2π)i
x1=1441372×cos(2arctan(−251)+π)+1441372×sin(2arctan(−251)+π)ix2=1441372×cos(2arctan(−251)+π+2π)+1441372×sin(2arctan(−251)+π+2π)ix1=−1441372×cos(2π−arctan(251))+1441372×sin(2arctan(251)+π)ix2=1441372×cos(2arctan(251)+π+2π)+1441372×sin(2arctan(251)+π+2π)i
Solution
x∈/R
Show Solution
