Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a)\(\left(x-3\right)\left(x+3\right)\left(x+2\right)-\left(x-1\right)\left(x^2-3\right)-5x\left(x+4\right)^2-\left(x-5\right)^2\)
\(=\left(x^2-9\right)\left(x+2\right)-\left(x^3-3x-x^2+3\right)-5x\left(x^2+8x+16\right)-\left(x^2-10x+25\right)\)
\(=x^3+2x^2-9x-18-x^3+x^2+3x-3-5x^3-40x^2-80x-x^2+10x-25\)
\(=-5x^3-38x^2-76x-46\)
b)\(2x\left(x-4\right)^2-\left(x+5\right)\left(x-2\right)\left(x+2\right)+2\left(x+5\right)^2-\left(x-1\right)^2\)
\(=2x\left(x^2-8x+16\right)-\left(x+5\right)\left(x^2-4\right)+2\left(x^2+10x+25\right)-\left(x^2-2x+1\right)\)
\(=2x^3-16x^2+32x-\left(x^3+5x^2-4x-20\right)+2x^2+20x+50-x^2+2x-1\)
\(=x^3-20x^2+58x+69\)
c)\(\left(x+5\right)^2-4x\left(2x+3\right)^2-\left(2x-1\right)\left(x+3\right)\left(x-3\right)\)
\(=x^2+10x+25-4x\left(4x^2+12x+9\right)-\left(2x-1\right)\left(x^2-9\right)\)
\(=x^2+10x+25-16x^3-48x^2-36x-\left(2x^3-x^2-18x+9\right)\)
\(=-18x^3-46x^2-8x+16\).
a) Ta có: \(\left(x-3\right)\left(x+3\right)\left(x+2\right)-\left(x-1\right)\left(x^2-3\right)-5x\left(x+4\right)^2-\left(x-5\right)^2\)
\(=\left(x^2-9\right)\left(x+2\right)-\left(x-1\right)\left(x^2-3\right)-5x\left(x^2+8x+16\right)-\left(x^2-10x+25\right)\)
\(=x^3+2x^2-9x-18-\left(x^3-3x-x^2+3\right)-5x^3-40x^2-80x-x^2+10x-25\)
\(=-4x^3-39x^2-79x-43-x^3+3x+x^2-3\)
\(=-5x^3-38x^2-76x-46\)
b) Ta có: \(2x\left(x-4\right)^2-\left(x+5\right)\left(x-2\right)\left(x+2\right)+2\left(x+5\right)^2-\left(x-1\right)^2\)
\(=2x\left(x^2-8x+16\right)-\left(x+5\right)\left(x^2-4\right)+2x^2+20x+50-x^2+2x-1\)
\(=2x^3-16x^2+32x-x^3+4x-5x^2+20+x^2+22x+49\)
\(=x^3-20x^2+56x+49\)
c) Ta có: \(\left(x+5\right)^2-4x\left(2x+3\right)^2-\left(2x-1\right)\left(x-3\right)\left(x+3\right)\)
\(=x^2+10x+25-4x\left(4x^2+12x+9\right)-\left(2x-1\right)\left(x^2-9\right)\)
\(=x^2+10x+25-16x^3+48x-36x-2x^3+18x+x^2-9\)
\(=-18x^3+2x^2+40x+16\)
a) A = (x+3)2 + (x-3)(x+3) - 2(x+2)(x - 4)
= (x + 3)(x + 3) + (x - 3)(x + 3) - 2[x(x - 4) + 2(x - 4)]
= x(x + 3) + 3(x + 3) + x(x + 3) - 3(x + 3) - 2[x2 - 4x + 2x - 8]
= x2 + 3x + 3x + 9 + x2 + 3x - 3x - 9 - 2(x2 - 2x - 8)
= x2 + 3x + 3x + 9 +x2 + 3x - 3x - 9 - 2x2 + 4x + 16
= (x2 + x2 - 2x2) + (3x + 3x + 3x - 3x + 4x) + (9 - 9 + 16) = 10x + 16
Thay x = -1/2 vào biểu thức trên ta có : \(10\cdot\left(-\frac{1}{2}\right)+16=-5+16=11\)
b) \(B=\left(3x+4\right)^2-\left(x-4\right)\left(x+4\right)-10x\)
\(B=9x^2+24x+16-x\left(x+4\right)+4\left(x+4\right)-10x\)
\(B=9x^2+24x+16-x^2-4x+4x+16-10x\)
\(B=\left(9x^2-x^2\right)+\left(24x-4x+4x-10x\right)+\left(16+16\right)\)
\(B=8x^2+14x+32\)
Thay x = -1/10 vào biểu thức trên ta có : \(B=8\cdot\left(-\frac{1}{10}\right)^2+14\cdot\left(-\frac{1}{10}\right)+32=\frac{767}{25}\)
c) \(C=\left(x+1\right)^2-\left(2x-1\right)^2+3\left(x-2\right)\left(x+2\right)\)
\(C=x^2+2x+1-\left(2x-1\right)\left(2x-1\right)+3\left(x^2-4\right)\)
\(C=x^2+2x+1-2x\left(2x-1\right)+1\left(2x-1\right)+3x^2-12\)
\(C=x^2+2x+1-4x^2+2x+2x-1+3x^2-12\)
\(C=\left(x^2-4x^2+3x^2\right)+\left(2x+2x+2x\right)+\left(1-1-12\right)\)
\(C=6x-12\)
Thay x = 1 vào biểu thức ta có : C = 6.1 - 12 = 6 -12 = -6
Còn bài kia làm nốt đi
Bạn đăng từng bài 1 và tách bài ra cho dễ nhìn hơn nhé!
3A:
a: =15x^4-5x^2-24x^4+18x^2-6x-6x^4+2x^3
=-15x^4+2x^3+13x^2-6x
b: =1/2(x^3-2/5x^2+2x)-3/4x^3-1/4x^2-x^2-x
=1/2x^3-1/5x^2+x-3/4x^3-5/4x^2-x
=-1/4x^3-29/20x^2
c: =3/2x^2(x^2-2x)-2x(x^3+x^2+1)+2(x-1)
=3/2x^4-3x^3-2x^4-2x^3-2x+2x-2
=-1/2x^4-5x^3-2
d: =x^4-2x^3+5x^3-10x^2+5/2x-x^4+x^3-x^2
=4x^3-11x^2+5/2x
a) 2x( x - 7 ) - ( x + 3 )( x - 2 ) - ( x + 4 )( x - 4 )
= 2x2 - 14x - ( x2 + x - 6 ) - ( x2 - 16 )
= 2x2 - 14x - x2 - x + 6 - x2 + 16
= 22 - 15x
b) ( 2x + 5 )( x - 2 ) - 3( x + 2 )2 + ( x + 1 )2
= 2x2 + x - 10 - 3( x2 + 4x + 4 ) + x2 + 2x + 1
= 3x2 + 3x - 9 - 3x2 - 12x - 12
= -9x - 21
c) ( x + 3 )( x - 3 ) - ( x + 5 )( x - 1 ) - ( x - 4 )2
= x2 - 9 - ( x2 + 4x - 5 ) - ( x2 - 8x + 16 )
= x2 - 9 - x2 - 4x + 5 - x2 + 8x - 16
= -x2 + 4x - 20
d) 2x( x + 1 )2 - ( x - 1 )3 - ( x - 2 )( x2 + 2x + 4 )
= 2x( x2 + 2x + 1 ) - ( x3 - 3x2 + 3x - 1 ) - ( x3 - 8 )
= 2x3 + 4x2 + 2x - x3 + 3x2 - 3x + 1 - x3 + 8
= 7x2 - x + 9
e) ( x + 5 )( x - 5 )( x + 2 ) - ( x + 2 )3
= ( x2 - 25 )( x + 2 ) - ( x3 + 6x2 + 12x + 8 )
= x3 + 2x2 - 25x - 50 - x3 - 6x2 - 12x - 8
= -4x2 - 37x - 58
\(a,=5x-10+2x+6=7x-4\\ b,=x^2+2x+1-x^2+3x+10=5x+11\\ c,=x^2-49-x^2+1=-48\\ d,\text{Đề có sai ko vậy?}\)