3. Fill in the blanks with one of the words in the box.
Small big smaller bigger biggest smallest
1. The double bass is the
of the violin family.
2. The cello is
than the double bass.
3. The cello is
than the viola.
4. The viola is not as
as the cello.
5. The violin is not as
as the viola.
6. The violin is the
of the violin family.
х²-2·4,5х+4,5²-4,5²+14=0
(х-4,5)²-6,25=0
(х-4,5)²-2,5²=0
Разложим на множители по формуле разности квадратов: a²-b²=(a-b)(a+b)
(x-4,5-2,5)(x-4,5+2,5)=0
(x-7)(x-2)=0
x-7=0 или х-2=0
х=7 или х=2
2)4x²-20x+21=0
(2х)²-2·2х·5+25-25+21=0
(2х-5)²-4=0
(2х-5)²-2²=0
(2х-5-2)(2х-5+2)=0
(2х-7)(2х-3)=0
2х-7=0 или 2х-3=0
х=3,5 или х=1.5
3)x²-11x+30=0
х²-2·5,5+5,5²-5,5²+30=0
(х-5,5)²-0,25=0
(х-5,5)²-0,5²=0
(х-5,5-0,5)(х-5,5+0,5)=0
(х-6)(х-5)=0
х-6=0 или х-5=0
х=6 или х=5
4)9x²-12x-5=0
(3х)²-2·3х·2+2²-2²-5=0
(3х-2)²-9=0
(3х-2)²-3²=0
(3х-2-3)(3х-2+3)=0
(3х-5)(3х+1)=0
3х-5=0 или 3х+1=0
х=5/3 или х=-1/3