42x^2/y^4*<span>у^2/14х^3=3/y^2*x</span>
Х+у=30=> х=30-у
х^2=у^2+180
(30-у)^2=у^2+180
у^2-60у+900=у^2+180
-60у=180-900
у=-720/(-60)
у=12
х=30-12=18
ответ; длины сторон квадратов 12см и 18см
<span>1) у=5-х
х^{2}- 15 +3x=-15
x^{2}+3x=0
x(x+3)=0
x=0 или х+3=0
х=-3 </span>y=5 x=-3<span>x=0 y=8</span>
<span>a) y=log5(x^2-5x+6), x^2-5x+6>0, x^2-5x+6=0 при х=2 х=3
2 3
____+____I_____-_______I______+______>
D(f)=(- ∞,2)U(3,+∞)
б)y=log2/3(-x^2-5x+14), </span><span>-x^2-5x+14>0, </span><span><span>-x^2-5x+14=0 при х=- 7, х=2
- -7 + 2 -
______I____________I______________></span>
D(f)=(-7, 2)
в)y=log9(x^2-13x+12), x^2-13x+12>0, </span><span><span>x^2-13x+12=0 при х=1, х=12
+ 1 - 12 +
______I_________I__________>
D(f)=(-∞,1)U(12,+∞)
</span>г)y=log0,2(-x^2+8x+9), </span><span>-x^2+8x+9>0, </span><span>-x^2+8x+9=0, x=-1, x=9
</span>
<span><span><span> - -1 + 9 -
______I____________I______________></span>
D(f)=(-1, 9)</span>
</span>
y= - x²-x+9
y=f(x)
1) f(2)= - 2²-2+9=3;
f(2)=3
2) f(-3)= - (-3)²-(-3)+9= -9+3+9 = 3;
f(-3)=3
3) (k;3)
x=k;
y= 3;
3 = -k² -k +9;
k² + k - 6 =0
D=1-4·1·(-6) = 1+24 = 25 = 5²
k₁ = (-1-5)/2= -3
k₂ = (-1+5)/2= 2
k₁ = -3
k₂ = 2