2b+49-2(b-7)=2b+49-(2b-14)=2b+49-2b+14={2b и -2b сокращаем}=49+14=63.
=25×11-(4×11)+7×5-(2×11)=275-128+35-22=160
1) (a-3)(a+8) = a²+8a-3a-24 = a² + 5a - 24
2) (-8-a)(b+2) =<span>-8b-ab-16-2a
</span>3) (8-y)(8+y)-(y²+4) = 64-y²-y²-4 = 60 - 2y²
4) (m-n+1)(m+n)
= m²+mn-mn+n²+m+n = m² + n² + m +n