Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Lời giải:
A) Tại $x=35$ thì \(x-35=0\)
\(A=x^3-15x^2+75x=x^3-35x^2+20x^2+75x\)
\(=x^3-35x^2+20x^2-700x+775x\)
\(=x^2(x-35)+20x(x-35)+775x\)
\(=775x=775.35=27125\)
B) \(x=-26\rightarrow x+26=0\)
\(B=x^3+18x^2+108x+16\)
\(=x^3+26x^2-8x^2-208x+316x+16\)
\(=x^2(x+26)-8x(x+26)+316x+16\)
\(=316x+16=316.-26+16=-8200\)
C)
\(C=(x^2-4y^2)(x^2-2xy+4y^2)(x^2+2xy+4y^2)\)
\(=(x-2y)(x+2y)(x^2-2xy+4y^2)(x^2+2xy+4y^2)\)
\(=[(x-2y)(x^2+2xy+4y^2)][(x+2y)(x^2-2xy+4y^2)]\)
\(=[x^3-(2y)^3][x^3+(2y)^3]\)
\(=(-8-1)(-8+1)=63\)
1. a) \(( 5x-1)^2 - (5x-4) ( 5x+4) = 7\)
\(\Leftrightarrow\)\(25x^2-10x+1-(25x^2-16)=7\)
\(\Leftrightarrow\)\(25x^2-10x+1-25x^2+16-7=0\)
\(\Leftrightarrow\)\(10x=10\)
\(\Rightarrow x=1\)
b) \(( 4x-1)^2 - (2x+3)^2 + 5(x+2)^2 + 3(x-2) ( x+2) = 500\)
\(\Leftrightarrow\)\(16x^2-8x+1-4x^2-12x-9+5x+10+3x^2-12=500\)
\(\Leftrightarrow\)\(15x^2-15x=510\)
\(\Leftrightarrow\)\(15(x^2-x)=510\)
\(\Leftrightarrow\)\(x^2-x=34\)
\(\Rightarrow x=-5,352349955\)
c) \((x-2)^3 - (x-2) ( x^2+2x+4 ) + 6(x-2)(x+2) = 60\)
\(\Leftrightarrow x^3-6x^2+12x-8-\left(x^3-2^3\right)+6\left(x^2-4\right)=60\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3+8+6x^2-24=60\)
\(\Leftrightarrow12x-24=60\)
\(\Leftrightarrow12x=84\)
\(\Rightarrow x=7\)
a; A = (7\(x\) + 5)2 + (3\(x-5\))2 - (10 - 6\(x\)).(5 + 7\(x\))
A = 49\(x^2\) + 70\(x\) + 25 + 9\(x^2\) - 30\(x\) + 25 - 50 - 70\(x\) + 30\(x\) + 42\(x^2\)
A = (49\(x^2\) + 9\(x^2\) + 42\(x^2\)) + (70\(x-70x\)) - (30\(x\) - 30\(x\)) + (25+25-50)
A = 100\(x^2\) + 0 + 0 + (50 - 50)
A = 100\(x^2\) + 0 + 0 + 0
A = 100\(x^2\)
Thay \(x=-2\) vào A = 100\(x^2\) ta có:
A = 100.(-2)2
A = 100.4
A = 400.
\(A=4y^2-\left(x^2-10x+25\right)\)
\(A=4y^2-\left(x-5\right)^2\)
\(A=\left(2y-x-5\right)\left(2y+x-5\right)\)
\(B=\left(x-4\right)^4-\left(x+a\right)^4\)
\(B=\left(\left(x-4\right)^2\right)^2-\left(\left(x+a\right)^2\right)^2\)
\(B=\left(\left(x-4\right)^2-\left(x+a\right)^2\right)\left(\left(x-4\right)^2+\left(x+a\right)^2\right)\)
\(B=\left(x-4\right)\left(x+a\right)\left(\left(x-4\right)^2+\left(x+a\right)^2\right)\)
\(C=\left(x^2+x\right)^2+2\left(x^2+x\right)+1\)
\(C=\left(x^2+x\right)\left(x^2+x+2\right)+1\)
2a) \(4x^2-1=\left(2x\right)^2-1^2=\left(2x+1\right)\left(2x-1\right)\)
b) \(x^2+16x+64=\left(x+8\right)^2\)
c) \(x^3-8y^3=x^3-\left(2y\right)^3\)
\(=\left(x-2y\right)\left(x^2+2xy+4y^2\right)\)
d) \(9x^2-12xy+4y^2=\left(3x-2y\right)^2\)
a) (x+4)(x2 - 4x + 16 ) - x(x-5) = 264
x3 + 43 - x(x2 - 25) = 264
x3 + 64 - x3 + 25x= 264
64 + 25x = 264
25x = 264-64
25x= 200
x = \(\dfrac{200}{25}\) = 8
b) (x-2)3 - (x-2)(x2 + 2x + 4 ) + 6(x-2)(x+2) = 60
x3 - 6x2 + 12x - 8 - ( x3 - 23 ) + 6(x2 - 4 ) = 60
x3 - 6x2 + 12x - 8 - x3 + 8 + 6x2 -24 = 60
12x - 24 = 60
12x = 60 + 24
12x = 84
x = \(\dfrac{84}{12}\) = 7