ដោះស្រាយ {l}{{(T)}=-9*10^{-8}*T^3+9*10^-6*T^2}{a=-7*10^-5*T+1000*2}{b=a}{c=b}{text{Solvefor}dtext{where}}{d=c}

$$\left. \begin{array} { l } { {(T)} = -9 \cdot 10 ^ {-8} \cdot T ^ {3} + 9 \cdot 10 ^ {-6} \cdot T ^ {2} }\\ { a = -7 \cdot 10 ^ {-5} \cdot T + 1000 \cdot 2 }\\ { b = a }\\ { c = b }\\ { \text{Solve for } d \text{ where} } \\ { d = c } \end{array} \right.$$

ដោះស្រាយសម្រាប់ T, a, b, c, d (complex solution)

$$T=0\text{, }a=2000\text{, }b=2000\text{, }c=2000\text{, }d=2000$$

$$T=\frac{50\sqrt{39991}i}{3}+50\approx 50+3332.958312237i\text{, }a=-\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965-0.233307082i\text{, }b=-\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965-0.233307082i\text{, }c=-\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965-0.233307082i\text{, }d=-\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965-0.233307082i$$

$$T=-\frac{50\sqrt{39991}i}{3}+50\approx 50-3332.958312237i\text{, }a=\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965+0.233307082i\text{, }b=\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965+0.233307082i\text{, }c=\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965+0.233307082i\text{, }d=\frac{7\sqrt{39991}i}{6000}+\frac{3999993}{2000}\approx 1999.9965+0.233307082i$$

ដោះស្រាយសម្រាប់ T, a, b, c, d

$$d=2000$$