1) (19/8 + 11/12) : 5/48 = (57/24 + 22/24) : 5/48 = 79/24 : 5/48 = 79/24 * 48/5 = 79 * 2 / 5 = 158/5 = 31,6
ОТВЕТ: 31,6
2) (-5х + 3)*(-х + 6) = 0
-5х + 3 = 0 ; -х + 6 = 0
-5х = -3 ; -х = -6
х1 = 0,6 ; х2 = 6
ОТВЕТ: 0,6 ; 6
Если надо упростить, то
исходное выражение=с²+81-с²=81
х^2+3х-(х^2+3х-5х-15)+ах-3а; 5х+15+ах-3а=0; 5х+15=3а-ах; %(х+3)=а(3-х); (х+3)*(3-х)*(5-а)=04 х=-3; х=3; а=5
4х²+36х+32=0
D=36²-4·4·32=1296-512=784=28²
x=(-36-28)/8=- 8 или х=(-38+28)/8=-5/4
Значит
![4 x^{2} +36x+32=4(x-(-8))\cdot (x-(- \frac{5}{4}))=(x+8)(5x+4), \\ \frac{x+8}{4 x^{2} +36x+32}= \frac{x+8}{(x+8)(5x+4)} = \frac{1}{5x+4}](https://tex.z-dn.net/?f=4+x%5E%7B2%7D+%2B36x%2B32%3D4%28x-%28-8%29%29%5Ccdot+%28x-%28-+%5Cfrac%7B5%7D%7B4%7D%29%29%3D%28x%2B8%29%285x%2B4%29%2C+%5C%5C++%5Cfrac%7Bx%2B8%7D%7B4+x%5E%7B2%7D+%2B36x%2B32%7D%3D+%5Cfrac%7Bx%2B8%7D%7B%28x%2B8%29%285x%2B4%29%7D+%3D+%5Cfrac%7B1%7D%7B5x%2B4%7D++)