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\(x^2+5x-6=x^2-x+6x-6=x\left(x-1\right)+6\left(x-1\right)=\left(x+6\right)\left(x-1\right)\)
\(5x^2+5xy-x-y=5x\left(x+y\right)-\left(x+y\right)=\left(5x-1\right)\left(x+y\right)\)
\(7x-6x^2-2=-\left(6x^2-7x+2\right)=-\left[\left(6x^2-3x\right)-\left(4x+2\right)\right]=-\left[3x\left(2x-1\right)-2\left(2x-1\right)\right]=-\left[\left(3x-2\right)\left(2x-1\right)\right]\)
d) \(x^2+4x+3=x^2+x+3x+3=x\left(x+1\right)+3\left(x+1\right)=\left(x+3\right)\left(x+1\right)\)
nhiều quá, các bn ngại làm, chia nhỏ ra,mk làm cho 2 câu
a) x2 +5x -6 = x2 -x +x + 5x -6
= x2 -x +6x -6
= x( x-1) + 6(x-1) = (x-1)(x+6)
b) 5x2 +5xy -x-y = 5x(x+y) -(x+y)
= (x+y)(5x-1)
c) 7x -6x2 -2 = 6( x+2/3)(x+1/2)
d) x2 +4x +3 = x2 +x +3x +3
= x(x+1) + 3(x+1)
= (x+1)(x+3)
a) x2 - 6x + 8 = x2 - 2x - 4x + 8 = x(x - 2) - 4(x - 2) = (x - 4)(x - 2)
b) x2 - 5x - 14 = x2 - 7x + 2x - 14 = x(x - 7) + 2(x - 7) = (x + 2)(x - 7)
c) 4x2 - 36x + 56 = 4(x2 - 9x + 14) = 4(x2 - 2x - 7x + 14) = 4[x(x - 2) - 7(x - 2)] = 4(x - 7)(x - 2)
d) 3x2 - 16x + 5 = 3x2 - 15x - x + 5 = 3x(x - 5) - (x - 5) = (3x - 1)(x - 5)
f) 8x2 + 30x + 7 = 8x2 + 16x + 14x + 7 = 8x(x + 2) + 7(x + 2) = (8x + 8)(x + 2)
g) 2x2 - 5xy - 12y2 = 2x2 - 8xy + 3xy - 12y2 = 2x(x - 4y) + 3y(x - 4y) = (2x + 3y)(x - 4y)
h) x2 - 7xy + 10y2 = x2 - 2xy - 5xy + 10y2 = x(x - 2y) - 5y(x - 2y) = (x - 5y)(x - 2y)
a)\(=\left(x-2\right)\left(5x-3x^2\right)\)
\(=x\left(x-2\right)\left(5-3x\right)\)
b)\(=\left(4x-x^2-4\right)\left(4x+x^2+4\right)\)
\(=-\left(x^2-4x+4\right)\left(x+2\right)^2\)
=\(-\left(x-2\right)^2\left(x+2\right)^2\)
c)\(\left(=5x^2-5xy\right)+\left(7y-7x\right)\)
\(=-5x\left(y-x\right)+7\left(y-x\right)\)
\(=\left(y-x\right)\left(7-5x\right)\)
d)\(=\left(3x^2-6x\right)-\left(2x-4\right)\)
\(=3x\left(x-2\right)-2\left(x-2\right)\)
\(=\left(x-2\right)\left(3x-2\right)\)
e)\(=[\left(x^2\right)^2+8^2+2.x^2.8]-2.8.x^2\)
\(=\left(x^2+8\right)^2-16x^2\)
\(=\left(x^2+8-4x\right)\left(x^2+8+4x\right)\)
__Chúc bạn hc tốt ......
1) \(16x\left(2-x\right)-\left(4x-5\right)^2=0\)
\(32x-16x^2-16x^2+40x-25=0\)
\(72x-16x^2-25=0\)
Đề sai ko bạn 
2) \(\left(x-7\right)^2+3=\left(x-2\right)\left(x+2\right)\)
\(\left(x^2-14x+7\right)+3-\left(x-2\right)\left(x+2\right)=0\)
\(x^2-14x+7+3-x^2+4=0\)
\(-14x+14=0\)
\(x=1\)
3) \(\left(2x-3\right)^2-\left(7x-2x\right)^2=2\)
\(\left(2x-3\right)^2-\left(5x\right)^2=2\)
\(\left(2x-3-5x\right)\left(2x-3+5x\right)=2\)
\(\left(-3x-3\right)\left(7x-3\right)=2\)
=> lập bảng tìm x
4) \(\left(5x-7\right)^2-\left(1-3x\right)^2=16x\left(x-3\right)\)
\(25x^2-70x+49-9x^2+6x-1-16x^2+48x=0\)
\(-16x+48=0\)
\(x=3\)
Tìm x:
\(5x\left(x-1\right)=x-1\)
\(5x\left(x-1\right)-\left(x-1\right)=0\)
\(\left(5x-1\right)\left(x-1\right)=0\)
\(\Rightarrow\)\(\left[{}\begin{matrix}5x-1=0\\x-1=0\end{matrix}\right.\)\(\Rightarrow\)\(\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=1\end{matrix}\right.\)
Vậy x=\(\dfrac{1}{5}\)hoặc x=1
\(2\left(x+5\right)-x^2-5x=0\)
\(2\left(x+5\right)-x\left(x+5\right)=0\)
\(\left(2-x\right)\left(x+5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2-x=0\\x+5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\)
Vậy...
A)\(x^2+5x-6=x^2-x+6x-6\\ =\left(x-1\right)\left(x+6\right)\)
B)\(5x^2+5xy-x-y=5x\left(x+y\right)-\left(x+y\right)\\ =\left(x+y\right)\left(5x-1\right)\)
C)\(7x-6x^2-2=-6x^2+3x+4x-2\\ =-3x\left(2x-1\right)+2\left(2x-1\right)=\left(2x-1\right)\left(2-3x\right)\)
D)\(x^2+4x+3=x^2+x+3x+3=\left(x+1\right)\left(x+3\right)\)
E)\(2x+3x-5=5x-5=5\left(x-1\right)\)
F)\(16x-5x^3=x\left(16-5x^2\right)\)
Mấy bài kia phá tung tóe rồi rút gọn hết sức xong thay x vào, làm câu c thôi nhé:
c) \(C=x^{14}-10x^{13}+10x^{12}-10x^{11}+...+10x^2-10x+10\)
riêng câu này ta thay x = 9 vào luôn, vậy ta có:
\(C=9^{14}-10\cdot9^{13}+10\cdot9^{12}-10\cdot9^{11}+...+10\cdot9^2-10\cdot9+10\)
\(=9^{14}-\left(9+1\right)\cdot9^{13}+\left(9+1\right)\cdot9^{12}-\left(9+1\right)\cdot9^{11}+...+\left(9+1\right)\cdot9^2-\left(9+1\right)\cdot9+10\)
\(=9^{14}-9^{14}-9^{13}+9^{13}+9^{12}-9^{12}-9^{11}+...+9^3+9^2-9^2-9+10\)
\(=-9+10\)
\(=1\)
a) x(x-5)+2(x-5) = (x-5)(x+2)
b) (x-7)(x-2)
c) (x+2)(x^2+2x+4)+5y(x+2) = (x+2)(x^2+2x+4+5y)
d) (x^2+8)^2 -16x^2 = (x^2+8-4x)(x^2+8+4x)