Решить lg2=0.301 lg5=0.699 найти сумму log2(50)+log5(40)

㏒2(50)+㏒5(40)=log2(25*2)+log5(8*5)=log2(5^2 * 2) +log5(2^3 *5)=
= (log2 (5^2)+log2(2) )+(log5(2^3) +log5 (5)) =2 log2 (5)+1 +3 log5 (2) +1=
2+ 2 lg5/lg2 +3 lg 2 /lg5≈
≈2+2*0.699/0.301+3*0.301/0.699≈2+2*0.699/0.301+3/(0.699/0.301)≈
≈2+2*2,322+3/2,322≈2+4.644+1.292=7.936
ответ: ≈ 7.936