5(b-7,4)=<span>3b+11
</span>5b+37 = 3b+11
<span>2b = - 26
b = -13</span>
замена 1/(x+2y)=u 1/y=v
5u+8v=5 I*2 10u+16v=10 вычтем друг из друга 18v=9 v=1/2
10u-2v=1 10u-2*1/2=1 10u=2 u=1/5
1/(x+2y)=1/5 x+2y=5 x+2*2=5 x=1
1/y=v y=2
ответ (1,2)
а) 6²-(7(n+2))²=(6-7(n+2))(6+7(n+2))= (-8-7n)(20+7n)= -(8+7n)(20+7n)
б) ((x+5)-3(x-1))((x+5)+3(x-1)) = (8-2x)(4x+2)
в) (2(3а²+2b)-(3a²-2b))(2(3a²+2b)+(3a²-2b)) = (3a²+6b)(9a²+2b)