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a/ \(3x^2-5x-2\)
\(=3x^2-3x-2x-2\)
\(=3x\left(x-1\right)+2\left(x-1\right)\)
\(=\left(x-1\right)\left(3x+2\right)\)
b/ \(2x^2+x-6\)
\(=2x^2+4x-3x-6\)
\(=2x\left(x+2\right)+3\left(x+2\right)\)
\(=\left(x+2\right)\left(2x+3\right)\)
c/ \(7x^2+50x+7\)
\(=7x^2+49x+x+7\)
\(=7x\left(x+7\right)+\left(x+7\right)\)
\(=\left(x+7\right)\left(7x+1\right)\)
d/ \(12x^2+7x-12\)
\(=12x^2-9x+16x-12\)
\(=3x\left(4x-3\right)+4\left(4x-3\right)\)
\(=\left(4x-3\right)\left(3x+4\right)\)
e/ \(15x^2+7x-2\)
\(=15x^2+10x-3x-2\)
\(=5x\left(3x+2\right)-\left(3x+2\right)\)
\(=\left(3x+2\right)\left(5x-1\right)\)
f/ \(a^2-5a-14\)
\(=a^2+2a-7a-14\)
\(=a\left(a+2\right)-7\left(a+2\right)\)
\(=\left(a+2\right)\left(a-7\right)\)
g/ \(2m^2+10m+8\)
\(=2m^2+2m+8m+8\)
\(=2m\left(m+1\right)+8\left(m+1\right)\)
\(=\left(m+1\right)\left(2m+8\right)\)
h/ \(4p^2-36p+56\)
\(=4p^2-28p-8p+56\)
\(=4p\left(p-7\right)-8\left(p-7\right)\)
\(=\left(p-7\right)\left(4p-8\right)\)
\(a,=\left(6x^3+3x^2-10x^2-5x+4x+2\right):\left(2x+1\right)\\ =\left[3x^2\left(2x+1\right)-5x\left(2x+1\right)+2\left(2x+1\right)\right]:\left(2x+1\right)\\ =3x^2-5x+2\\ b,Sửa:\left(2x^3-21x^2+67x-60\right):\left(x-5\right)\\ =\left(2x^3-10x^2-11x^2+55x+12x-60\right):\left(x-5\right)\\ =\left[2x^2\left(x-5\right)-11x\left(x-5\right)+12\left(x-5\right)\right]:\left(x-5\right)\\ =2x^2-11x+12\)
Bài 1: a) x2 - 5x + 6 = x2 - 2x - 3x + 6 = x(x - 2) - 3(x - 2) = (x - 3)(x - 2)
b) 3x2 + 9x - 30 = 3x2 + 15x - 6x - 30 = 3x(x + 5) - 6(x + 5) = (3x - 6)(x + 5) = 2(x - 2)(x + 5)
c) x2 - 3x + 2 = x2 - 2x - x + 2 = x(x - 2) - (x - 2) = (x - 1)(x - 2)
d) x2 - 9x + 18 = x2 - 3x - 6x + 18 = x(x - 3) - 6(x - 3) = (x - 6)(x - 3)
e) x2 - 6x + 8 = x2 - 2x - 4x + 8 = x(x - 2) - 4(x - 2) = (x - 4)(x - 2)
f) x2 - 5x - 14 = x2 - 7x + 2x - 14 = x(x - 7) + 2(x - 7) = (x + 2)(x - 7)
g) x2 + 6x + 5 = x2 + 5x + x + 5 = x(x + 5) + (x + 5) = (x + 1)(x + 5)
h) x2 - 7x + 12 = x2 - 3x - 4x + 12 = x(x - 3) - 4(x - 3) = (x - 4)(x - 3)
i) x2 - 7x + 10 = x2 - 2x - 5x + 10 = x(x - 2) - 5(x - 2) = (x - 5)(x - 2)
Oh Sehun:Ít một thôi bạn ơi!Làm xong đống này chắc đến tuổi già mất:(
a
\(x^2-5x+6\)
\(=\left(x^2-3x\right)-\left(2x-6\right)\)
\(=\left(x-3\right)\left(x-2\right)\)
b
\(3x^2+9x-30\)
\(=x^2+3x-10\)
\(=\left(x^2-2x\right)+\left(5x-10\right)\)
\(=\left(x-2\right)\left(x+5\right)\)
c
\(x^2-3x+2\)
\(=\left(x^2-x\right)-\left(2x-2\right)\)
\(=\left(x-1\right)\left(x-2\right)\)
d
\(x^2-9x+18\)
\(=\left(x^2-3x\right)-\left(6x-18\right)\)
\(=\left(x-3\right)\left(x-6\right)\)
e
\(x^2-6x+8\)
\(=\left(x^2-2x\right)-\left(4x-8\right)\)
\(=\left(x-2\right)\left(x-4\right)\)
f
\(x^2-5x-14\)
\(=\left(x^2+2x\right)-\left(7x+14\right)\)
\(=\left(x+2\right)\left(x-7\right)\)
g
\(x^2+6x+5\)
\(=\left(x^2+x\right)+\left(5x+5\right)\)
\(=\left(x+1\right)\left(x+5\right)\)
h
\(x^2-7x+12\)
\(=\left(x^2-3x\right)-\left(4x-12\right)\)
\(=\left(x-3\right)\left(x-4\right)\)
i
\(x^2-7x+10\)
\(=\left(x^2-2x\right)-\left(5x-10\right)\)
\(=\left(x-2\right)\left(x-5\right)\)
P/S:Cho e xin phép tách câu ạ.
a) 5x(10x+7)-25x(2x-3) = 40
50x2+35x-50x2+75x = 40
(50x2-50x2)+(35x+75x) = 40
110x = 40
x =\(\dfrac{40}{110}\)=\(\dfrac{4}{11}\)
b)
Bài 2:
a) x + 2a.(x-y) - y
= 2a.(x-y) + (x-y)
= (x-y).(2a+1)
b) 5a2 - 5ax - 7a + 7x
= 5a.(a-x) - 7.(a-x)
= (a-x).(5a-7)
Bài 1:
a) 5x.(10x+7) - 25x.(2x-3) = 40
50x2 + 35x - 50x2 + 75x = 40
110x = 40
x = 4/11
b) (3x+2).(x-2) - (x-1).(x-3) = 4
3x2 - 6x + 2x - 4 - x2 + 3x + x - 3 = 4
2x2 - 7 = 4
...
bn tự làm tiếp nha
a.\(2x\left(7x^2-5x-1\right)=14x^3-10x^2-2x\)
b.\(-2x^3\left(2x^2-3y+5yz\right)=-4x^5+6x^3y-10x^3yz\)
c.\(\left(2x-y\right)\left(4x^2-2xy+y^2\right)=2x\left(4x^2-2xy+y^2\right)-y\left(4x^2-2xy+y^2\right)\)
\(=8x^2-4x^2y+4xy^2-4x^2y+2xy^2-y^3\)
a.2x(7x2−5x−1)=14x3−10x2−2x
b.−2x3(2x2−3y+5yz)=−4x5+6x3y−10x3yz
c.(2x−y)(4x2−2xy+y2)=2x(4x2−2xy+y2)−y(4x2−2xy+y2)
=8x2−4x2y+4xy2−4x2y+2xy2−y3
2x^2 + x - 6
= 2x^2 + 4x - 3x - 6
= 2x(x + 2) - 3(x + 2)
= (2x - 3)(x + 2)
7x^2 + 50x + 7
= 7x^2 + x + 49x + 7
= 7x(x + 7) + x + 7
= (7x + 1)(x + 7)
12x^2 + 7x - 12
15x^2 + 7x - 2
= 15x^2 - 3x + 10x - 2
= 3x(5x - 1) + 2(5x - 1)
= (3x + 2)(5x - 1)
a^2 - 5a - 14
= a^2 + 2a - 7a - 14
= a(a + 2) - 7(a + 2)
= (a - 7)(a + 2)
2x^2 + 5x + 2
= 2x^2 + x + 4x + 2
= 2x(x + 2) + x + 2
= (2x + 1)(x + 2)
\(2x^2+x-6=2x^2+4x-3x-6\)
\(=2x\left(x+2\right)-3\left(x+2\right)\)
\(=\left(x+2\right)\left(2x-3\right)\)
\(7x^2+50x+7\)
\(=7x^2+x+49x+7\)
\(=x\left(7x+1\right)+7\left(7x+1\right)\)
\(=\left(7x+1\right)\left(x+7\right)\)
\(12x^2+7x-12\)
\(=12x^2+16x-9x-12\)
\(=4x\left(3x+4\right)-3\left(3x+4\right)\)
\(=\left(3x+4\right)\left(4x-3\right)\)