(oxed~ eginarrayrcll ax^2+bx+c &=& 0\ x &=& dfrac-b pm sqrtb^2-4ac 2a \ endarray ~)
(eginarrayrcll x^2+3x+4 &=& 0 qquad & a=1 quad b=3 quad c = 4 \\ x &=& frac-3 pm sqrt3^2-4cdot 1 cdot 4 2cdot 1 \\ x &=& frac-3 pm sqrt9-16 2 \\ x &=& frac-3 pm sqrt-7 2 qquad &| quad sqrt-7=sqrt-1cdot 7=sqrt-1sqrt7\\ x &=& frac-3 pm sqrt-1sqrt7 2 qquad &| quad sqrt-1 = i \\ x &=& frac-3 pm isqrt7 2 \\ mathbfx_1 &mathbf=& mathbf-frac32 + fracsqrt72cdot i \\ mathbfx_2 &mathbf=& mathbf-frac32 - fracsqrt72cdot i endarray)
heureka Mar 31, 2016
5+0 Answers
#1
0
Plugging this into WolframAlpha gives me this (admittedly dubious) answer.
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x = 1/2*i*(sqrt(7)+3i
x = 1/2*i*(sqrt(7)-3i
Guest Mar 31, 2016
#2
0
impossible. Graph it.
Guest Mar 31, 2016
edited byGuest Mar 31, 2016
#3
0
solve for x, can use quadratic formula, factoring, completing the square etc.
http://www.dummies.com/how-to/content/how-to-factor-a-polynomial-expression.html
doesn"t factor, use quadratic formula or complete the square
completing the square:
x^2+3x+4 = 0 Note: ax^2+bx+c (a, b & c are constants not variables lượt thích x)
x^2+3x = -4
x^2+3x+2.25=-4+2.25 Note: (b/2)^2 = c 3/2 = 1.5, 1.5^2 = 2.25 (add 2.25 to both sides lớn keep the equation the same)
(x+1.5)^2 = 1.75 Note: x^2+3x+2.25 using complete the square is (x+1.5)^2
sqrt(x+1.5^2)= sqrt(1.75) Note: Again, same operation khổng lồ both sides, square root lớn keep the equation the same
x+1.5 = (plus or minus)sqrt(1.75)
x = (plus or minus)sqrt(1.75) - 1.5
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Guest Mar 31, 2016
#4
0
solve for x, can use quadratic formula, factoring, completing the square etc.
http://www.dummies.com/how-to/content/how-to-factor-a-polynomial-expression.html
doesn"t factor, use quadratic formula or complete the square
completing the square:
x^2+3x+4 = 0 Note: ax^2+bx+c (a, b và c are constants not variables like x)
x^2+3x = -4
x^2+3x+2.25=-4+2.25 Note: (b/2)^2 = c 3/2 = 1.5, 1.5^2 = 2.25 (add 2.25 to lớn both sides khổng lồ keep the equation the same)
(x+1.5)^2 = -1.75 Note: x^2+3x+2.25 using complete the square is (x+1.5)^2
sqrt(x+1.5^2)= sqrt(-1.75) Note: Again, same operation to both sides, square root khổng lồ keep the equation the same
x+1.5 = (plus or minus) sqrt(-1.75)
x = (plus or minus) sqrt(-1.75) - 1.5
carry negative sign* it does exist just not a real number it is an imaginary number
Guest Mar 31, 2016
#5
+10
Best Answer
x^2+3x+4=0 what does the x equal? please solve
(oxed~ eginarrayrcll ax^2+bx+c &=& 0\ x &=& dfrac-b pm sqrtb^2-4ac 2a \ endarray ~)
(eginarrayrcll x^2+3x+4 &=& 0 qquad và a=1 quad b=3 quad c = 4 \\ x &=& frac-3 pm sqrt3^2-4cdot 1 cdot 4 2cdot 1 \\ x &=& frac-3 pm sqrt9-16 2 \\ x &=& frac-3 pm sqrt-7 2 qquad &| quad sqrt-7=sqrt-1cdot 7=sqrt-1sqrt7\\ x &=& frac-3 pm sqrt-1sqrt7 2 qquad &| quad sqrt-1 = i \\ x &=& frac-3 pm isqrt7 2 \\ mathbfx_1 &mathbf=& mathbf-frac32 + fracsqrt72cdot i \\ mathbfx_2 &mathbf=& mathbf-frac32 - fracsqrt72cdot i endarray)
heureka Mar 31, 2016
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