数学2,3题

Question

如题所述

Answer 1

2(1)解：(x+1)(x-2)=0
∴x+1=0或x-2=0
则x=-1或x=2追答

(2)解：(x-2)(x-6)=0
∴x-2=0或x-6=0
则x=2或x=6
(3)解：x² - 3x + 2=0
(x-1)(x-2)=0
∴x-1=0或x-2=0
则x=1或x=2
(4)解：x² + 4x - 21=0
(x+7)(x-3)=0
∴x+7=0或x-3=0
则x=-7或x=3

3(1)解：x² - 13x + 36=0
(x-4)(x-9)=0
∴x-4=0或x-9=0
则x=4或x=9
(2)解：(x-3)(7x-2)=0
∴x-3=0或7x-2=0
则x=3或x=2/7
(3)解：3x(2x-5) + 4(2x-5)=0
(2x-5)(3x+4)=0
∴2x-5=0或3x+4=0
则x=5/2或x=-4/3
(4)解：(x-3)²=0
∴x-3=0
则x=3

Answer 2

2.
1) x^2-x-2=0
(x+1)(x-2)=0
x1=-1,x2=2
2) x^2-8x+12=0
(x-2)(x-6)=0
x1=2,x2=6
3) x^2+2=3x
x^2-3x+2=0
(x-1)(x-2)=0
x1=1,x2=2
4) x^2+4x=21
x^2+4x-21=0
(x-3)(x-7)=0
x1=3,x2=-7
3.
1) 13x=x^2+36
x^2-13x+36=0
(x-4)(x-9)=0
x1=4,x2=9
2) 7x(x-3)-2(x-3)=0
(7x-2)(x-3)=0
x1=2/7,x2=3
3) 3x(2x-5)-4(5-2x)=0
(2x-5)(3x+4)=0
x1=5/2,x2=-4/3
4) x^2-6x+9=0
(x-3)(x-3)=0
x=3