(5x-1)(5x+1)=25x2-7x+15
<=> 25x2-1-25x2+7x-15=0
<=>7x=16
=>x=16/7
(5x-1)(5x+1)=25x^2-7x+15
(5x-1)(5x+1)-25x^2+7x-15=0
(5x)^2-1^2-25x^2+7x-15=0
25x^2-1-25x^2+7x-15=0
7x-16=0
7x=16
x=16:7
x=16/7.vay x=16/7
Phân tích các đa thức sau thành nhân tử.
1) a^2+ab+2b-4 2) x^3-x 3) x^2-6x+8 4) ab+b^2-3a-3b 5) x^3-4x^2-8x+8
6)9x^2+6x-8 7)x^2-y^2-4x+4 8)5x^3-10x^2+5x 9) 3x^2-8x+4 10) 4x^2-4x-3
11) x^2-7x+12 12)x^2-5x-14 13) 3x^2-7x+2 14) a.(x^2+1)-x.(a^2-1) 15) x^4+4
16) (x+2).(x+3).(x+4).(x+5)-24 17) (a+1).(a+3).(a+5).(a+7)+15
thu gọn biểu thức
a) (6x-2)2+4(3x-1)(2+y)+(y+2)2-(6x+y)2
b)5(2x-1)2+2(x-1)(x+3)-2(5-2x)2-2x(7x+12)
c)2(5x-1)(x2-5x+1)+(x2-5x+1)2+(5x-1)2-(x2-1)(x2+1)
d)(x2+4)2-(x2+4)(x2-4)(x2+16)-8(x-4)(x+4)
Tìm GTNN ( cần gấp)
15/ x2 + x + 1
16/ x2 - 3x + 1
17/ x2 + 5x - 6
18/ x2 - 7x+ 8
Tìm x biết
1, (3x-5)2 + (2x+1)2 = (5x-6)(2x+3)+ 3x2
2, (7x-4)(5x+3)= (6x-5)2 - x2 +1
Bài 1: Thực hiện phép tính
1, (3y +1/3y^4)^2
2, (-3x^2 -1/2x)^2
3, (x^2 +2x -3)^2
4, 3 (x+3) (x-3) - (x-9)^2
5, (x^n +x^n:1)^2
6, (5x-3y)^2 - (5x +3y)^2
7, (3x -x^2 +5)^2
8, (-2x +5y)^3
9, (1/3x^2 -5y^3)^3
10,(m^2n^3+n^2m^3) (m^2n^3 - n^2m^3)
11, (7x+6y)^2 - (7x +6y) (7x -6y)
12, (x-y)^2 +(y+x)^2 - (2x -y)^z
13, (a-b)^3 + (a+b)^3
14, (a-b)^3 -(a-b)^3
15, (3x-5y)^4 - (3x +5y)^4
Mọi người làm giúp mình vs
Bài 1: dùng hằng đẳng thức
a) x2 + 5x - 6
b) 7x - 6x2 -2
c) 5x( x-1) - 3x(x-1)
d) (3x + 1)2 - (x+1)2
e) x6 - y6
Tìm x biết
1. 2(5x-8)-3(4x-5)=4(3x-4)+11
2. (2x+1)2-(4x-1).(x-3)-15=0
3. (3x-1).(2x-7)-(1-3x).(6x-5)=0
Bai 1: Giai phuong trinh
a, (x - 2)3 - (x - 3) (x2 + 3x + 9) +6 ( x + 1)2 = 15
b, (5x + 1)2 - (5x + 3) (5x - 3) = 30
c, (x + 3) (x2 - 3x + 9) - x (x - 2) (x+ 2 ) = 15
GIUP MINH VOI ! THANK YOU !^^
Rút gọn :
1. (2x-5)(3x+1)-(x-3)^2+(2x+5)^2-(3x+1)^3
2. (2x-1)(2x+1)-3x-2)(2x+3)-(x-1)^3+(2x+3)^3
3. (x-2)(x^2+2x+4)-(3x-2)^3+(3x-4)^2
4. (7x-1)(8x+2)-(2x-7)^2-(x-4)^3-(3x+1)^3
5. (5x-1)(5x+1)-(x+3)(x^2-3x+9)-(2x+4)^2-(3x-4)^2+(2x-5)^3
6. (4x-1)(x+2)-(2x+5)^2-(3x-7)^2+(2x+3)^3=(3x-1)^3
