Х(х+3)-4(х-5)=7(х+4)-8
x²+3x-4x+20=7x+28-8
x²-x-7x=20-20
x²-8x=0
D=64-4×1×0
D=64
x₁=8-8/2=0
x₂=8+8/2=8
<span>Ответ: х₁=0, х₂=8 </span>
45 деталей - 100%
х деталей - 120 %
х = 120·45 :100= 54 (дет.)
Ответ: 54 детали изготовил рабочий.
4/45 : (12/25 - 4/15) + 15/16 * 4/15 = 2/3
1) 12/25 - 4/15 = 36/75 - 20/75 = 16/75
2) 4/45 : 16/75 = 4/45 * 75/16 = (1*5)(3*4) = 5/12
3) 15/16 * 4/15 = 4/16 = 1/4
4) 5/12 + 1/4 = 5/12 + 3/12 = 8/12 = 2/3