ответ:
d=b^2-4ac=(-1)^2-4*1*(-72)=1+288=\sqrt{289}
289
=17
х1=\frac{-b- \sqrt{d} }{2a} = \frac{1-17}{2} = \frac{-16}{2} =-8
2a
−b−
d
=
2
1−17
−16
=−8
х2=\frac{-b+ \sqrt{d} }{2a} = \frac{1+17}{2} = \frac{18}{2} = 9
−b+
1+17
18
=9
ответ: -8 и 9
d=b^2-4ac=7^2-4*(-4)*(-3)=49-48=\sqrt{1} =1
1
=1
х1=\frac{-b- \sqrt{d} }{2a} = \frac{-7-1}{2*(-4)} = \frac{-8}{-8} =1
2∗(−4)
−7−1
−8
х2=\frac{-b+ \sqrt{d} }{2a} = \frac{-7+1}{(-8)} = \frac{-6}{-8} =0,75
(−8)
−7+1
−6
=0,75
(10-x)/(x²-3x-2)≥(10-x)/(x²-4x-5)
(10-x)(x²-4x-5-x²+3x+2)/(x²-3x-2)(x²-4x-5)≥0
(10-x)(-x-3)/(x²-3x-2)(x²-4x-5)≥0
10-x=0⇒x=10
-x-3=0⇒x=-3
x²-3x-2=0⇒D=9+8=17⇒x1=(3-√17)/2 U x2=(3+√17)/2
x²-4x-5-0⇒x1+x2=4 U x1*x2=-5⇒x1=-1 U x2=5
+ _ + _ + _ +
-3 -1 (3-√17)/2 (3+√17)/2 5 10
x∈(-≈;-3] U (-1;(3-√17)/2) U ((3+√17)/2;;5) U x=10
2)x>10
(x-10)/(x²-3x-2)≥(10-x)/(x²-4x-5)
(x-10)(x²-4x-5-x²+3x+2)/(x²-3x-2)(x²-4x-5)≥0
(x-10)(-x-3)/(x²-3x-2)(x²-4x-5)≥0
x-10=0⇒x=10
-x-3=0⇒x=-3
x²-3x-2=0⇒D=9+8=17⇒x1=(3-√17)/2 U x2=(3+√17)/2
x²-4x-5-0⇒x1+x2=4 U x1*x2=-5⇒x1=-1 U x2=5
_ + _ + _ + _
-3 -1 (3-√17)/2 (3+√17)/2 5 10
Решения на промежутке (10;≈) нет
ответ:
d=b^2-4ac=(-1)^2-4*1*(-72)=1+288=\sqrt{289}
289
=17
х1=\frac{-b- \sqrt{d} }{2a} = \frac{1-17}{2} = \frac{-16}{2} =-8
2a
−b−
d
=
2
1−17
=
2
−16
=−8
х2=\frac{-b+ \sqrt{d} }{2a} = \frac{1+17}{2} = \frac{18}{2} = 9
2a
−b+
d
=
2
1+17
=
2
18
=9
ответ: -8 и 9
d=b^2-4ac=7^2-4*(-4)*(-3)=49-48=\sqrt{1} =1
1
=1
х1=\frac{-b- \sqrt{d} }{2a} = \frac{-7-1}{2*(-4)} = \frac{-8}{-8} =1
2a
−b−
d
=
2∗(−4)
−7−1
=
−8
−8
=1
х2=\frac{-b+ \sqrt{d} }{2a} = \frac{-7+1}{(-8)} = \frac{-6}{-8} =0,75
2a
−b+
d
=
(−8)
−7+1
=
−8
−6
=0,75