The problem presents three equations: 1. $6x^3 + x^2 - 19x + 6 = 0$

AlgebraPolynomial EquationsCubic EquationsQuartic EquationsRational Root TheoremPolynomial DivisionQuadratic Formula
2025/5/22

1. Problem Description

The problem presents three equations:

1. $6x^3 + x^2 - 19x + 6 = 0$

2. $9x^3 + 10x^2 - 17x = 2$

3. $x^4 - 9x^2 - 4x + 12 = 0$

We need to find the solutions for each equation.

2. Solution Steps

Let's solve each equation separately.
Equation 1: 6x3+x219x+6=06x^3 + x^2 - 19x + 6 = 0
We can try to find a rational root using the Rational Root Theorem. The possible rational roots are ±1,±2,±3,±6,±12,±32,±13,±23,±16\pm 1, \pm 2, \pm 3, \pm 6, \pm \frac{1}{2}, \pm \frac{3}{2}, \pm \frac{1}{3}, \pm \frac{2}{3}, \pm \frac{1}{6}.
Let's try x=12x = \frac{1}{2}:
6(12)3+(12)219(12)+6=6(18)+14192+6=34+14384+244=3+138+244=10406(\frac{1}{2})^3 + (\frac{1}{2})^2 - 19(\frac{1}{2}) + 6 = 6(\frac{1}{8}) + \frac{1}{4} - \frac{19}{2} + 6 = \frac{3}{4} + \frac{1}{4} - \frac{38}{4} + \frac{24}{4} = \frac{3+1-38+24}{4} = \frac{-10}{4} \neq 0
Let's try x=23x = \frac{2}{3}:
6(23)3+(23)219(23)+6=6(827)+49383+6=169+491149+549=16+4114+549=40906(\frac{2}{3})^3 + (\frac{2}{3})^2 - 19(\frac{2}{3}) + 6 = 6(\frac{8}{27}) + \frac{4}{9} - \frac{38}{3} + 6 = \frac{16}{9} + \frac{4}{9} - \frac{114}{9} + \frac{54}{9} = \frac{16+4-114+54}{9} = \frac{-40}{9} \neq 0
Let's try x=3x = -3:
6(3)3+(3)219(3)+6=6(27)+9+57+6=162+9+57+6=162+72=9006(-3)^3 + (-3)^2 - 19(-3) + 6 = 6(-27) + 9 + 57 + 6 = -162 + 9 + 57 + 6 = -162 + 72 = -90 \neq 0
Let's try x=2x = 2:
6(2)3+(2)219(2)+6=6(8)+438+6=48+438+6=5838=2006(2)^3 + (2)^2 - 19(2) + 6 = 6(8) + 4 - 38 + 6 = 48 + 4 - 38 + 6 = 58 - 38 = 20 \neq 0
Let's try x=3/2x = 3/2.
6(3/2)3+(3/2)219(3/2)+6=6(27/8)+(9/4)57/2+6=81/4+9/4114/4+24/4=(81+9114+24)/4=0/4=06(3/2)^3 + (3/2)^2 - 19(3/2) + 6 = 6(27/8) + (9/4) - 57/2 + 6 = 81/4 + 9/4 - 114/4 + 24/4 = (81+9-114+24)/4 = 0/4 = 0. So x=3/2x = 3/2 is a root.
Now we can divide the polynomial by (x3/2)(x - 3/2) or (2x3)(2x - 3).
(6x3+x219x+6)/(2x3)=3x2+5x2(6x^3 + x^2 - 19x + 6) / (2x - 3) = 3x^2 + 5x - 2
Now we solve the quadratic equation 3x2+5x2=03x^2 + 5x - 2 = 0.
Using the quadratic formula:
x=b±b24ac2a=5±524(3)(2)2(3)=5±25+246=5±496=5±76x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{-5 \pm \sqrt{5^2 - 4(3)(-2)}}{2(3)} = \frac{-5 \pm \sqrt{25 + 24}}{6} = \frac{-5 \pm \sqrt{49}}{6} = \frac{-5 \pm 7}{6}
So x=5+76=26=13x = \frac{-5+7}{6} = \frac{2}{6} = \frac{1}{3} and x=576=126=2x = \frac{-5-7}{6} = \frac{-12}{6} = -2.
Therefore, the solutions to the first equation are x=3/2,x=1/3,x=2x = 3/2, x = 1/3, x = -2.
Equation 2: 9x3+10x217x=2    9x3+10x217x2=09x^3 + 10x^2 - 17x = 2 \implies 9x^3 + 10x^2 - 17x - 2 = 0
Let's try x=2x = -2: 9(2)3+10(2)217(2)2=9(8)+10(4)+342=72+40+342=74+74=09(-2)^3 + 10(-2)^2 - 17(-2) - 2 = 9(-8) + 10(4) + 34 - 2 = -72 + 40 + 34 - 2 = -74 + 74 = 0
So x=2x = -2 is a root.
Divide the polynomial by (x+2)(x + 2):
(9x3+10x217x2)/(x+2)=9x28x1(9x^3 + 10x^2 - 17x - 2) / (x + 2) = 9x^2 - 8x - 1
Now we solve the quadratic equation 9x28x1=09x^2 - 8x - 1 = 0.
Using the quadratic formula:
x=b±b24ac2a=8±(8)24(9)(1)2(9)=8±64+3618=8±10018=8±1018x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{8 \pm \sqrt{(-8)^2 - 4(9)(-1)}}{2(9)} = \frac{8 \pm \sqrt{64 + 36}}{18} = \frac{8 \pm \sqrt{100}}{18} = \frac{8 \pm 10}{18}
So x=8+1018=1818=1x = \frac{8+10}{18} = \frac{18}{18} = 1 and x=81018=218=19x = \frac{8-10}{18} = \frac{-2}{18} = -\frac{1}{9}.
Therefore, the solutions to the second equation are x=2,x=1,x=1/9x = -2, x = 1, x = -1/9.
Equation 3: x49x24x+12=0x^4 - 9x^2 - 4x + 12 = 0
Let's try integer roots.
Let's try x=1x = 1: 149(1)24(1)+12=194+12=1313=01^4 - 9(1)^2 - 4(1) + 12 = 1 - 9 - 4 + 12 = 13 - 13 = 0
Let's try x=1x = -1: (1)49(1)24(1)+12=19+4+12=179=80(-1)^4 - 9(-1)^2 - 4(-1) + 12 = 1 - 9 + 4 + 12 = 17 - 9 = 8 \neq 0
Let's try x=2x = 2: 249(2)24(2)+12=16368+12=2844=1602^4 - 9(2)^2 - 4(2) + 12 = 16 - 36 - 8 + 12 = 28 - 44 = -16 \neq 0
Let's try x=2x = -2: (2)49(2)24(2)+12=1636+8+12=3636=0(-2)^4 - 9(-2)^2 - 4(-2) + 12 = 16 - 36 + 8 + 12 = 36 - 36 = 0
So x=1x = 1 and x=2x = -2 are roots.
Thus (x1)(x - 1) and (x+2)(x + 2) are factors.
(x1)(x+2)=x2+x2(x - 1)(x + 2) = x^2 + x - 2
Now divide x49x24x+12x^4 - 9x^2 - 4x + 12 by x2+x2x^2 + x - 2:
(x49x24x+12)/(x2+x2)=x2x6(x^4 - 9x^2 - 4x + 12) / (x^2 + x - 2) = x^2 - x - 6
Now solve the quadratic equation x2x6=0x^2 - x - 6 = 0.
(x3)(x+2)=0(x - 3)(x + 2) = 0
So x=3x = 3 and x=2x = -2.
Therefore, the solutions to the third equation are x=1,x=2,x=3,x=2x = 1, x = -2, x = 3, x = -2.
The solutions are x=1,x=2,x=3x = 1, x = -2, x = 3.

3. Final Answer

Equation 1: x=3/2,1/3,2x = 3/2, 1/3, -2
Equation 2: x=2,1,1/9x = -2, 1, -1/9
Equation 3: x=1,2,3x = 1, -2, 3

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