Let's solve each equation separately.
Equation 1: 6x3+x2−19x+6=0 We can try to find a rational root using the Rational Root Theorem. The possible rational roots are ±1,±2,±3,±6,±21,±23,±31,±32,±61. Let's try x=21: 6(21)3+(21)2−19(21)+6=6(81)+41−219+6=43+41−438+424=43+1−38+24=4−10=0 Let's try x=32: 6(32)3+(32)2−19(32)+6=6(278)+94−338+6=916+94−9114+954=916+4−114+54=9−40=0 Let's try x=−3: 6(−3)3+(−3)2−19(−3)+6=6(−27)+9+57+6=−162+9+57+6=−162+72=−90=0 6(2)3+(2)2−19(2)+6=6(8)+4−38+6=48+4−38+6=58−38=20=0 Let's try x=3/2. 6(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=3/2 is a root. Now we can divide the polynomial by (x−3/2) or (2x−3). (6x3+x2−19x+6)/(2x−3)=3x2+5x−2 Now we solve the quadratic equation 3x2+5x−2=0. Using the quadratic formula:
x=2a−b±b2−4ac=2(3)−5±52−4(3)(−2)=6−5±25+24=6−5±49=6−5±7 So x=6−5+7=62=31 and x=6−5−7=6−12=−2. Therefore, the solutions to the first equation are x=3/2,x=1/3,x=−2. Equation 2: 9x3+10x2−17x=2⟹9x3+10x2−17x−2=0 Let's try x=−2: 9(−2)3+10(−2)2−17(−2)−2=9(−8)+10(4)+34−2=−72+40+34−2=−74+74=0 So x=−2 is a root. Divide the polynomial by (x+2): (9x3+10x2−17x−2)/(x+2)=9x2−8x−1 Now we solve the quadratic equation 9x2−8x−1=0. Using the quadratic formula:
x=2a−b±b2−4ac=2(9)8±(−8)2−4(9)(−1)=188±64+36=188±100=188±10 So x=188+10=1818=1 and x=188−10=18−2=−91. Therefore, the solutions to the second equation are x=−2,x=1,x=−1/9. Equation 3: x4−9x2−4x+12=0 Let's try integer roots.
Let's try x=1: 14−9(1)2−4(1)+12=1−9−4+12=13−13=0 Let's try x=−1: (−1)4−9(−1)2−4(−1)+12=1−9+4+12=17−9=8=0 Let's try x=2: 24−9(2)2−4(2)+12=16−36−8+12=28−44=−16=0 Let's try x=−2: (−2)4−9(−2)2−4(−2)+12=16−36+8+12=36−36=0 So x=1 and x=−2 are roots. Thus (x−1) and (x+2) are factors. (x−1)(x+2)=x2+x−2 Now divide x4−9x2−4x+12 by x2+x−2: (x4−9x2−4x+12)/(x2+x−2)=x2−x−6 Now solve the quadratic equation x2−x−6=0. (x−3)(x+2)=0 So x=3 and x=−2. Therefore, the solutions to the third equation are x=1,x=−2,x=3,x=−2. The solutions are x=1,x=−2,x=3.