4x²+bx-15=0; x1=5.
По т.Виета
x1*x2=-15;
5*x2=-15;
x2=-15/5=-3.
x1+x2=-b;
-b=5+(-3)=2;
b=-2;
Ответ: b=-2.
17^12-49^6=17^12-(7^2)^6=17^12-7^12=(17^6)^2-(7^6)^2=(17^6-7^6)(17^6+7^6),
17^6-7^6=(17^2)3-(7^2)^3=(17^2-7^2)(17^4+17^2*7^2+7^4)=(17-7)(17+7)*
*(17^4+17^2*7^2+7^4)=10*24*(17^4+17^2*7^2+7^4)
17^12-7^12=(17-7)(..........)
<span>2m(m-n)+m-n=2m²-<u>2mn</u>+m-<u>n</u>=m(2m+1)-n(2m+1)=(m-n)(2m+1)
</span><span>a(x-c)+bc-bx=ax-ac+bc-bx=x(a-b)-c(a-b)=(x-c)(a-b)
</span>2m(m-n)-n+m=2m²-2mn-n+m=m(2m+1)-n(2m+1)=<span>(m-n)(2m+1)
</span>3a(2b+c)+8b+4c=6ab+3ac+8b+4c=2b(3a+4)+c(3a+4)=(2b+3a)(<span>3a+4)</span>
<span>(9*3n)/(3n+1+3n-1)=
=(9*3)/(3+3)n=
=(9*3n)/6n=
=9/2=
=4.5</span>