rút gọn: ( 4x + 5 ) 2 - 2 ( 4x + 5 ) ( x + 5 ) + ( x + 5 )2
Rút gọn
\(\left(4x+5\right)^2-2.\left(4x+5\right)\left(x+5\right)+\left(x+5\right)^2\)
\(\left[\left(4x+5\right)-\left(x+5\right)\right]^{^2}=\left(4x+5-x-5\right)^2=\left(3x\right)^2=9x^2\)
Rút gọn:
a) ( 4x + 5 )2 - 2(4x+5)(x+5) + (x+5)2
b) Tìm GTLN: 3x - x2 - 4
a)\(\left(4x+5\right)^2-2\left(4x+5\right)\left(x+5\right)+\left(x+5\right)^2\)
\(=\left(4x+5-x-5\right)^2=\left(3x\right)^2=9x^2\)
b) \(3x-x^2-4\)
\(=-x^2+2.x.1,5-2,25+2,25-4\)
\(=-\left(x-1,5\right)^2-1,75\le-1,75\)
Dấu bằng xảy ra khi : \(x-1,5=0\)
\(x=1,5\)
Vậy GTLN của biểu thức trên bằng -1,75 khi x = 1,5
\(2x^3\left(x^2-5\right)+\left(-2x^3+4x\right)+\left(6+x\right)x^2\)
\(=2x^5-10x^3-2x^3+4x+6x^2+x^3=2x^5-9x^3+6x^2+4x\)
rút gọn: x^2+x-6/x^2+4x+3 : x^2-10x+25/x^2-4x-5 GIÚP MIK VS MIK ĐAG CẦN GẤP
Em bấm vào biểu tượng \(\sum\) trên thanh công cụ và gõ phân số để mn dễ hỗ trợ nhé!
`(x^2+x-6)/(x^2+4x+3):(x^2-10x+25)/(x^2-4x-5)(x ne -1,x ne 5,x ne -3)`
`=((x-2)(x+3))/((x+1)(x+3)):(x-5)^2/((x+1)(x-5))`
`=(x-2)/(x+1):(x-5)/(x+1)`
`=(x-2)/(x-5)`
\(\dfrac{x^2+x-6}{x^2+4x+3}=\dfrac{\left(x+3\right)\left(x-2\right)}{\left(x+3\right)\left(x+1\right)}=\dfrac{x-2}{x+1}\)
\(\dfrac{x^2-10x+25}{x^2-4x-5}=\dfrac{\left(x-5\right)^2}{\left(x-5\right)\left(x+1\right)}=\dfrac{x-5}{x+1}\)
tính(rút gọn)
4x^2-(x+3)(x-5)+x
Bài 1. Tìm \(x\).
a) -5(\(x\)2-3\(x\)+1)+\(x \)(1+5\(x\))=\(x-2\)
b) \(12x\)2\(-4x\)\((3x+5)\)\(=10x-17\)
c) \(-4x(x-5)+7x(x-4)-3x\)2\(=12\)
Bài 2. Tính ( Rút gọn).
a) \((x+5).(x-7)-7x.(x-3)\)
b) \(x.(x\)2\(-x-2)-(x-5).(x+1)\)
c) \((x-5).(x-7)-.(x+4).(x-3)\)
d) \((x-1).(x-2)-(x+5).(x+2)\)
Bài 1:
a) \(-5\left(x^2-3x+1\right)+x\left(1+5x\right)=x-2\)
\(\Rightarrow-5x^2+15x-5+x+5x^2=x-2\)
\(\Rightarrow16x-5=x-2\)
\(\Rightarrow16x-x=5-2\)
\(\Rightarrow15x=3\)
\(\Rightarrow x=\dfrac{15}{3}=5\)
b) \(12x^2-4x\left(3x+5\right)=10x-17\)
\(\Rightarrow12x^2-12x^2-20x=10x-17\)
\(\Rightarrow-20x=10x-17\)
\(\Rightarrow-20x-10x=-17\)
\(\Rightarrow-30x=-17\)
\(\Rightarrow x=\dfrac{-30}{-17}=\dfrac{30}{17}\)
c) \(-4x\left(x-5\right)+7x\left(x-4\right)-3x^2=12\)
\(\Rightarrow-4x^2+20x+7x^2-28x-3x^2=12\)
\(\Rightarrow-8x=12\)
\(\Rightarrow x=\dfrac{12}{-8}=-\dfrac{4}{3}\)
Bài 2:
a) \(\left(x+5\right)\left(x-7\right)-7x\left(x-3\right)\)
\(=x^2-7x+5x-35-7x^2+21x\)
\(=-6x^2+19x-35\)
b) \(x\left(x^2-x-2\right)-\left(x-5\right)\left(x+1\right)\)
\(=x^3-x^2-2x-x^2+x-5x-5\)
\(=x^3-2x^2-6x-5\)
c) \(\left(x-5\right)\left(x-7\right)-\left(x+4\right)\left(x-3\right)\)
\(=x^2-7x-5x+35-x^2-3x+4x-12\)
\(=11x+23\)
d) \(\left(x-1\right)\left(x-2\right)-\left(x+5\right)\left(x+2\right)\)
\(=x^2-2x-x+2-x^2+2x+5x+10\)
\(=4x+12\)
rút gọn
b/ (3x – 5)2 – 4x(x + 2) – 5x(x – 3) – 37x
\(=9x^2-30x+25-4x^2-8x-5x^2+15x-37x=5x^2-60x+25\)
rút gọn biểu thức
a) (2x + 1)(x – 3) – 4x(5 – 2x)
b) (x + 2)2 – 2(x + 3)(x - 3) + 10
c) (4x – 3)(2 – x 2 ) – 2(x – 3)2 – 7x3
a: \(=2x^2-6x+x-3-20x+8x^2\)
\(=10x^2-25x-3\)
b: \(=x^2+4x+4-2\left(x^2-9\right)+10\)
\(=x^2+4x+14-2x^2+18\)
\(=-x^2+4x+32\)
(x+5).(x-4)-(x+2)^2+(2x+3)^3= (4x^2+1)+18(2x+3) rút gọn
Rút gọn phân thức x 2 + 4 x + 4 9 - ( x + 5 ) 2
A. - x - 2 x + 8
B. x - 2 x + 8
C. - x + 2 x + 8
D. x - 2 x - 8