1) (4a-b)(a-6b)+a(25b-3a)=4a²-24ab-ab+6b²+25ab-3a²=
4a²-<u>25ab</u>+<u>25ab</u>+6b²-3a²=<u>4a²</u>-<u>3a²</u>+6b²=<u>a²+6b²
</u>
2) (2x+3y)(x-y)-x(x+y)=2x²<u>-2xy</u>+<u>3xy</u>-3y²-x²<u>-xy=</u>2x²-x²-3y²=x²-3y²
3) 3a(a+1)+(a+2)(a-3)=<u>3a²</u>+3a+<u>a²</u>-3a+2a-6=<u>4a²+2a-6
</u>4) 2c(5c-3)-(c-2)(c-4)=<u>10c²-</u>6c-<u>c</u>²+4c+2c-8=9c²<u>-6c</u>+<u>4c</u>+<u>2c</u>-8=<u>9c²-8</u>
Ответ:....................
2(x^2-10xy+25)///////////
<span>1)2Cos</span>²<span>3</span>α <span>- Cos6</span>α = 2Cos²3α - 2Cos²α +1 = 1<span>
2) 2Cos</span>²α<span>/ 1+ Cos2</span>α= 2Cos²α/(1 + 2Cos²α -1) = 2Cos²α/2Cos²α = 1<span>
3) 1 - Cos (</span>π <span>- 2</span>α<span>)/ 1 - Sin</span>²α = 1+Cos2α/Сos²α= (1 +2Cos²α -1)/Cos²α =2<span>
4) Cos2 </span>α<span> + Sin</span>²α<span>/ 1 - Sin</span>²α= (Cos²α - Sin²α + Sin²α)/Сos²α = 1