Ta có: \(a+b+c=2x\)
\(\Rightarrow\left(a+b+c\right)^2=4x^2\)
\(\Rightarrow a^2+b^2+c^2+2ab+2bc+2ac=4x^2\)
\(VP=4x\left(x-a\right)\)
\(=4x^2-4xa\)
\(=a^2+b^2+c^2+2ab+2bc+2ac-\left(2a+2b+2c\right)a\)
\(=a^2+b^2+c^2+2ab+2bc+2ac-2a^2-2ab-2ac\)
\(=2bc+b^2+c^2-a^2=VT\)
\(\Rightarrowđpcm\)
Cho a+b+c=2p
CMR: 2ab+\(b^2+c^2-a^2=4p\)(p-a)
Giups mk vs ạ ai nhanh mk sẽ vote nha
Cho a+b+c=2p.Chứng minh hằng đẳng thức:
2ab+b2+c2-a2=4p(p-a)
Chứng minh rằng:
a) \(\left(a+b\right)^2=a^2+2ab+b^2\)
b) \(\left(a-b\right)^2=a^2-2ab+b^2\)
c) \(\left(a-b\right)\left(a+b\right)=a^2-b^2\)
C/M đẳng thức sau
1 (a-b)^2 =a^2-2ab+b^2
2 (a-b)(a+b)=a^2-b^2
\(\left(a+b-c\right)^2-\left(a-c\right)^2-2ab+2bc\)
Rút gọn biểu thức :
a, A = ( x - y ) ( x^2 + xy + y^2 ) - ( x + y ) ( x^2 - xy + y^2 )
b, B = ( a^2b^2 - 5a ) ( a^4 + b^4 + 5a^3b^2 + 25d^2 )
c, C = ( 2x + 3y ) ( 4x^2 - 6xy + 9y^2 )
d, D = ( y + 2 ) ( y^2 - 2y + 4 )
Bài 1: Nhân
a) 4x(3x-1)-2(3x+1)-(x+3)
b) (-2x^2-1xy+2y^2)(-1x^2y)
c) 4x(3x^2-x) -(2x+3)^2(6x^2-3x+1)
d) (x-2)(x+2)(x+4)
Bài 2: Tìm x
a) 4x(x-1)-3(x^2-5)-x^2=(x-3)(x+4)
b) 2(3x-1)(2x+5-6)(2x-1)(x+2)=6
c) 3(2x-1)(3x-1)-(2x-3)(9x-1)-3=-3
Bài 1:Phân tích các đa thức sau thành nhân tử:
a) 14x2 – 21xy2 + 28x2y2 = 7x(2x - 3y2 + 4xy2)
b) 2(x + 3) – x(x + 3) = (x + 3)(2 - x)
c) x2 + 4x – y2 + 4 = (x + 2)2 - y2 = (x + 2 - y)(x + 2 + y)
Bài 2: Làm phép tính:
a, (a+b) . (a+b)
b, (a-b) . (a+b)
c, (a-b) . (a-b)
P/s: Mk cần gấp !!!
BT lam tinh nhan
a)(x^3+2x^2y-5xy^2-3y^3)(5x-4y)
b)(x+1)(x-2)(2x-1)
c)(2x+y)(4x^2-2xy+y^2)
d)(a^3+a^2b+ab^2+b^3)(a-b)
