ОДЗ
x > 2
lg = log_10
log_10 (x - 2) > log_10 (1000)
x - 2 > 1000
x > 1002
+ ОДЗ
x > 1002
Ответ
<span>x </span>∈ ( 1002; + ∞)
1.
(x-4)²-(x+9)²=195
x²-8x+16-(x²+18x+81)=195
x²-8x+16-x²-18x-81=195
-26x=195-16+81
-26x=260
x=-10
Ответ x=-10.
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2.
x+7x²-y-7y²=(x-y)+7(x²-y²)=(x-y)+7(x-y)(x+y)=(x-y)(1+7x+7y)
Ответ: (x-y)(7x+7y+1).
Xn = x1 + (n-1)*d
n = ?
(xn-x1 +d) = n*d
(xn-x1+d)/d = n
n = (-2.6 - 8.2 - 0.3) / (-0.3) = 37