1)7-2x-x^2)-(x-2)(x+3)=7-2x-x^2-x^2-x+6=-2x^2-3x+13
2)(3m^2+3n^2)-(2m+n)(m+2n)=3m^2+3n^2-2m^2-5mn-2n^2=m^2-5mn+n^2
3)u(u+v)-(v-1)(u-1)=u^2++uv-uv+v+u-1=u^2+v+u-1
4)x^2+1)(x^2+2)=x^4+2x^2+x^2+2=x^4+3x^2+2
5)3+b^3)(b^3-4)=3b^3-12+b^6-4b^3=b^6-b^3-12
3x*2-6/2(x+1)=x-11
6x-3(x+1)=x-11
6x-3x-3=x-11
3x-3=x-11
3x-x=-11+3
2x=-8
x=-4
<span>(0,5x^2-3xy)+(3xy-x^2+2)=0,5х^2-x^2+2=-0.5x^2+2
-0.5*2^2+2=-2+2=0
</span>
<h3>Hello Friend,</h3>
5.1 = 2^2 + 3^2 = 4+9 = 13
5.2 = 2^3 + 3^3 = 12 + 27 = 39
5.3 = 2^4 + 3^4 = 24+81= 105
5.4 = 2^2+(a*b=-3)+3^2=4-3+9=10
5.5 = 2^3*3^2+2^2*3^3=12*9+4*27=108+108=216