Bài làm:
Ta có: \(\left(10^2+8^2+...+2^2+1^2\right)-\left(9^2+7^2+...+1^2\right)\)
\(=\left(10^2-9^2\right)+\left(8^2-7^2\right)+...+\left(2^2-1^2\right)+1\)
\(=\left(10-9\right)\left(10+9\right)+\left(8-7\right)\left(8+7\right)+...+\left(2-1\right)\left(2+1\right)+1\)
\(=19.1+15.1+...+3.1+1\)
\(=1+3+7+11+15+19\)
\(=56\)
(10^2+8^2+6^2+4^2+2^2)-(9^2+7^2+5^2+3^2+1^2)
(10^2+8^2+6^2+4^2+2^2)-(9^2+7^2+5^2+3^2+1^2)
(10^2+8^2+6^2+4^2+2^2)-(9^2+7^2+5^2+3^2+1^2)
1.giải các phương trình sau:
a, 3(2x+1)/4 - 5x+3/6 = 2x-1/3 - 3-x/4
b, 19/4 - 2(3x-5)/5 = 3-2x/10 - 3x-1/4
c, x-2*3/2+3 + x-3*5/3+5 + x-5*2/5+2 = 10
d, x-3/5*7 + x-5/3*7 + x-7/3*5 = 2(1/3 + 1/5 + 1/7)
2. giải các phương trình:
a, x-1/9 + x-2/8 = x-3/7 + x-4/6
b, (1/1*2 + 1/2*3 + 1/3*4 + ... + 1/9*10) (x-1) + 1/10x = x- 9/10
Tính nhanh (10^2+8^2+6^2+4^2+2^2)-(9^2+7^2+5^2+3^2+1^2)
Phân tích đa thức thành nhân tử:
1.45+x^3-5*x^2-9*x
2.x^4-2*x^3-2*x^2-2*x+3
3.x^4-5*x^2+4
4.x^4+64
5.x^5+x^4+1
6.(x^2+2*x)*(x^2+2*x+4)+3
7.(x^3+4*x+8)^2+3*x*(x^2+4*x+8)+2*x^2
8. x^3*(x^2-7)^2-36*x
9.x^5+x+1
10. x^8+x^4+1
11. x^5-x^4-x^3-x^2-x-2
12. x^9-x^7-x^6-x^5+x^4+x^3+x^2-1
13. (x^2-x)^2-12*(x^2-x)+24
Giải phương trình
1) (3x-2)/3-2=(4x+1)/4
2) (x-3)/4+(2x-1)/3=(2-x)/6
3) 1/2 (x+1)+1/4 (x+3)=3-1/3 (x+2)
4) (x+4)/5-x+4=x/3-(x-2)/2
5) (4-5x)/6=2(-x+1)/2
6) (-(x-3))/2-2=5(x+2)/4
7)2(2x+1)/5-(6+x)/3=(5-4x)/15
8) (7-3x)/2-(5+x)/5=1
9)(x-1)/2+3(x+1)/8=(11-5x)/3
10)(3+5x)/5-3=(9x-3)/4
các bạn giúp mik bài này vs
5) (4x-5).(x+2)-(x+5).(x-3)-3x^2-x
6) (x-3).(x+7)-(2x-1).(x+2)+x.(x-1)
7) (7x-3).(2x+1)-(5x-2).(x+4)-9x^2+17x
8) -2.(x-7).(x+3)+(5x-1).(x+4)-3x^2-27x
9) (6x-5).(x+8)-(3x-1).(2x+3)-9.(4x-3)
10) (8x-1).(x+7)-(x-2).(8x+5)-11.(6x+1).
phân tích đa thức thành nhân tử
1)2x^2+3x-5
2)16-5x^-3
3)x^2+x-6
4)x^2+8x-9
5)x^2+x-12
6)x^8+1024
7)x^7+x^2+1
8)x^8+3x^4+4
9)(x^2+x+1)(x^2+x+2)-12
10)x(x+1)(x+2)(x+3)+1
11)x^4+6x^3+11x^2+6x+1
12)3x^2+11x^3-7x^2-2x+1
