Lim (2x-8) / ((√x+5)-3)
x→4
lim 2х-8
x→4
lim (√x+5)-3
x→4
2×4-8 = 0
(√4+5)-3 = √9 - 3 = 0
0
0
lim (2x-8) / ((√x+5)-3)
x→4
lim ((2x-8)×((√x+5)+3)) / ((√x+5)-3)×((√x+5)-3))
x→4
lim (2(x-4)×((√x+5)+3)) / x+5-9
x→4
lim (2(x-4)×((√x+5)+3)) / x-4
x→4
lim 2((√x+5)+3)
x→4
lim 2((√4+5)+3)
x→4
2(√9 +3)
2(3+3)
6 + 6 = 12
Ответ: 12
1. 1) (х²+4)²-16х² = (х²+4)² - (4х)² = ((х²+4)-4х)((х²+4)+4х) = (х²-4х+4)(х²+4х+4) = (х-2)²(х+2)²
2) (а²+9)²-36а² = (а²+9)²-(6а)² = (а²+9-6а)(а²+9+6а) = (а-3)²(а+3)²
3) (а²+с⁴)²-4а²с⁴ = (а²+с⁴)²-(2ас²)² = (а²+с⁴-2ас²)(а²+с⁴+2ас²) = (а-с²)²(а+с²)²
4) (4m⁴+n²)²-16m⁴n² = (4m⁴+n²)²-(4m²n)² = (4m⁴+n²-4m²n)(4m⁴+n²+4m²n) = (2m²-n)²(2m²+n)²
2. 1) а²+2аb+b²-1 = (a²+2ab+b²) - 1= (a+b)²-1² = (a+b-1)(a+b+1)
2) х²-2ху+у²-4 = (х²-2ху+у²)-4 = (х-у)² - 2² = (х-у-2)(х-у+2)
3) 4m²-20mn+25n²-36 =((2m)²-2*2m*5n+(5n)²)-36 = (2m-5n)²-6² = (2m-5n-6)(2m-5n+6)
4) 16a²+24ab+9b²-25 = ((4a)²+2*4a*3b+(3b)²)-25 = (4a+3b)²-5² = (4a+3b-5)(4a+3b+5)
<span>8(х-3)-4(5х+2)=5х+19,
8х-8·3-4·5х-4·2=5х+19,
8х-24-20х-8=5х+19,
8х-20х-5х=19+24+8,
-17х=51,
х=51:(-17)
х=-3
</span>
-2(х-4)не=0; х не=4;
x^2+1=-13(-2x+8),
x^2+1=26x-104,
x^2-26x+105=0,
D=169-105=64,
x(1)=13+8=21,
x(2)=13-8=5.