1.
1)
38² - 64 = 38² - 8² = (38 - 8)(38 +8) = 30 * 46 = 1380,
2.
1)
2в² - 18 = 2 * (в² - 9) = 2 * (в - 3)(в + 3),
3)
81х² - 18ху + у² + 63х - 7у = (81х² - 18ху + у²) + (63х - 7у) =
= (9х - у)² + 7*(9х - у) = (9х - у)(9х - у + 7),
4)
m² + n² + 2mn = (m + n)².
3.
а)
(8 - 2n)(8 + 2n) + (9 + 2n)² - 64 = 64 - 4n² + 81 + 36n + 4n² - 64 =
= 36n + 81 = 9(4n + 9),
б)
(3х - 8)² + (4х - 8)(4х + 8) = 9х² - 48х + 64 + 16х² - 64 = 25х² - 48х,
при х=-2:
25 * (-2)² - 48 * (-2) = 100 + 96 = 196,
4.
1 число - х,
2 число - (х+2),
(х+2)² - х² = 188,
х² + 4х + 4 - х² = 188,
4х = 184,
х = 46 - 1 число,
х+2 = 46+2 = 48 - 2 число
3x^2-2=0 3х²=3 D=81+88=169
3x^2=2 х²=1 x1=(-9+13)/2=2
x^2=2/3 x=1 x2=(-9-13)/2=-11
x=√2/3
5)5х²+9х+4=0 6)7х²-11х-6=0 7)х²- 12х+32=0
D=81-80=1 D=121+168=289 d=144-128=16
x1=(-9+1)/2=-4 x1=11+17)/14=2 x1=12+4)/2=8
x2=(-9-1)/2=-5 x2=11-17)/14=-3/7 x2=12-4)/2=4
8)36х²-12+1=0 9) 3х²+х-2=0
d=144-144=0 d=1+24=25
x=12/72=1/6 x1=-1+5)/6=2/3
x2=-1-5)/6=-1