![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(5\left(x+2\right)\left(x-2\right)-\left(2x-3\right)^2-x^2+17=5\left(x^2-4\right)-\left(4x^2-12x+9\right)-x^2+17=12x-12\)
5(x+2)(x−2)−(2x−3)2−x2+17(x2−4)−(4x2−12x+9)−x2+17=12x−12
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=x\left(9x^2-16\right)-9\left(x^3+8\right)+16x\\ A=9x^3-16x-9x^3-72+16x\\ A=-72\)
\(A=x\left(3x-4\right)\left(3x+4\right)-9\left(x+2\right)\left(x^2-2x+4\right)+16x\)
\(=x\left(9x^2-16\right)-9\left(x^3+8\right)+16x\)
\(=9x^3-16x-9x^3-72+16x=-72\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
$A=x[(3x)^2-4^2]-9(x^3+2^3)+16x$
$=x(9x^2-16)-9(x^3+8)+16x$
$=9x^3-16x-9x^3-72+16x$
$=-72$
\(A=x\left(3x-4\right)\left(3x+4\right)-9\left(x+2\right)\left(x^2-2x+4\right)+16x\)
\(=9x^3-16x-9x^3-72+16x\)
=-72
![](https://rs.olm.vn/images/avt/0.png?1311)
a. \(\left(x+2\right)^{^2}-\left(x-4\right)^{^2}+x^{^2}-3x+1=x^{^2}+4x+4-x^{^2}+8x-16+x^{^2}-3x+1=x^{^2}+9x-11\)
b. \(\left(2x+2\right)^{^2}-4x\left(x+2\right)=4x^{^2}+8x+4-4x^{^2}-8x=4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
5( x+2 ) . ( x-2 ) -12 .( 6 - 8x )2 +17
=5.x^2-2^2-12*6^2
Do x>=17 nên |x-17|>=0
Do đó |x-17|=x-17
=>A=x-17+18-x
=>A=1
Chúc em học tốt^^
Khi \(x\ge17\)thì \(x-17\ge0\)hay \(\left|x-17\right|=x-17\)
\(\Rightarrow A=x-17+18-x=1\)
tk nka !!11