Question

Как решить х(17-х)=72

Answer 1

$x(17 - x) = 72 \\ 17x - x {}^{2} = 72 \\ - x {}^{2} + 17x - 72 = 0 | \times ( - 1) \\ x { }^{2} - 17x + 72 = 0 \\ d = 289 - 4 \times 72 = 289 - 288 = 1 \\ x1 = \frac{17 + 1}{2} = 9 \\ x2 = \frac{17 - 1}{2} = 8$

Answer 2

x(17-x)=72

17x-x²-72=0
x²-17x+72=0

D=289-288=1

x=(17±1)/2

x1=9;x2=8