1) (а-12)³ - 125=(a-12)³-5³=(a-12-5)((a-12)²+(a-12)*5+5²)=
=(a-17)(a²-24a+144+5a-60+25)=
=(a-17)(a²-19a+109)
2)(b+4)³+64=(b+4)³+4³=(b+3+4)((b+3)²+(b+3)*4+4²)=
=(b+7)(b²+6b+9+4b+12+16)=
=(b+7)(b²+10b+37)
3)81-(с²+6с)²=9²-(c²+6c)²=(9+c²+6c)(9-c²-6c)=(c+3)²(9-c²-6c)
<span>4)16m</span>²<span>-(m-n)</span>²=(4m)²-(m-n)²=(4m+m-n)(4m-m+n)=(5m-n)(3m+n)
![cos x=\frac{\sqrt{3}}{2};\\\\x=^+_-arccos \frac{\sqrt{3}}{2} +360^0*k;\\\\x=^+_-30^o+360^0*k;](https://tex.z-dn.net/?f=cos+x%3D%5Cfrac%7B%5Csqrt%7B3%7D%7D%7B2%7D%3B%5C%5C%5C%5Cx%3D%5E%2B_-arccos+%5Cfrac%7B%5Csqrt%7B3%7D%7D%7B2%7D+%2B360%5E0%2Ak%3B%5C%5C%5C%5Cx%3D%5E%2B_-30%5Eo%2B360%5E0%2Ak%3B)
k є Z
на промежутке [270; 350] решения будут :![330^o;](https://tex.z-dn.net/?f=330%5Eo%3B)
3,2у - 0.6 = 2.7у =1.1у-0.2 +0.8
3.2у-2.7у-1.1у= 0.8-0.2+0.6
-0.6у=1.2
у= 1.2 : -0.6
у=2