8/7x-10/3=-5/21
x:27=-2:3,6
Tìm x
(3x-3)(.5-21x)+(7x +4)(6x-5)=45
(x+1)(x+2)(x+5)-x^2(x+8)=27
tìm x biết :
a) (3x-3).(5-21x)+(7x+4).(9x-5) = 44
b) (x+1).(x+2).(x+5) - \(x^2\).(x+8) = 27
\(a)\left(3x-3\right)\left(5-21x\right)+\left(7x+4\right)\left(9x-5\right)=44\\ \Leftrightarrow15x-63x^2-15+63x+63x^2-35x+36x-20=44\\ \Leftrightarrow79x-35=44\\ \Leftrightarrow79x=79\Rightarrow x=1\)
\(b)\left(x+1\right)\left(x+2\right)\left(x+5\right)-x^2\left(x+8\right)=27\\ \Leftrightarrow x^2+2x+x+2\left(x+5\right)-x^3-8x^2=27\\ \Leftrightarrow x^2\left(x+5\right)+2x\left(x+5\right)+x\left(x+5\right)+2\left(x+5\right)-x^3-8x^2=27\\ \Leftrightarrow x^3+5x^2+2x^2+10x+x^2+5x+2x+10-x^3-8x^2=27\\ \Leftrightarrow17x+10=27\\ \Leftrightarrow17x=17\Rightarrow x=1\)
câu 6: (x-5)(x-4)=10-2x
câu 7:(x ²+1)(x-2)+2x=4
câu 8:(x+3)(x ²-3x+9)=7x ³+21x
Câu 7:
\(\Leftrightarrow\left(x-2\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=1\\x=-1\end{matrix}\right.\)
6, (x-5).(x-4)=10-2x
(x-5).(x-4)+2(x-5)=0
(x-5)(x-2)=0
=>x=5, x=2
7, (x^2+1)(x-2)+2x=4
x^3-2x^2+x-2+2x=4
x^3-2x^2+3x-2-4=0
x^3-2x^2+3x-6=0
x^2(x-2)+3(x-2)=0
(x-2)(x^2+3)=0
th1: x=2
th2: x^2+3>0 với mọi x thuộc Z
8, ( đề cs sai hông , giải hong ra:>)
a,(3x-3) (5-21x)+(7x+4) (9x-5)=44
b,(x+1) (x+2) (x+5)-x^2 (x+8)=27
c, cho A=x^100+x^99+x^98+...+x+1 CMR:Ax-A=X^101-1
d) (5x+3) ( 4x-1) +(10x-7) (-2x+3) =27
e)(8x-5) (3x+2) -(12x+7) (2x-1)=17
f) (5x+9) (6x-1) -(2x-3)( 15z+1) = -190
g) 6x(5x+3) + 3x(1-10x) =7
h) (3x-3) (5 -21x) +(7x+4)(9x-5) =44\
i) (x+1)(x+2)(x-5)-x2 (x+8)=27
một đòn bẫy dài một mét .đặt ở đâu để có thể dùng 3600n có thể nâng tảng đá nặng 120kg?
phân tích đa thức thành nhân tử bằng phương pháp tách hạng tử :
1) x^3 + 5x^2 + 3x - 9
2) x^3 + 9x^2 + 11x - 21
3) x^3 + 4x^2 - 7x - 10
4) x^5 - 5y^3 + 4x
5) 4x^4 - 21x^27^2 + y^4
chân thành cảm ơn ạ
mình cần gấp lắm
Bài 1 : chứng minh rằng các biểu thức sau đây không phụ thuộc vào x a,A=(3x+7)(2x+3)-(2x+3)-(3x-5)(2x+11) b,B=(x^2-2)(x^2+x-1)-x(x^3+x^2-3x-2) Bài 2:Tìm x biết: a,6x(5x+3)+3x(1-10x)=7 b,(3x-3)(5-21x)+(7x+4)(9x-5)=44 c,(x+1)(x+2)(x+5)-x^2(x+8)=27 d,(2x-1)(3-x)+(x-2)(x+3)=(1-x)(x+2) Bài 3 Tính a,(2x+3)^3 b,(x-3y)^3 c.(x+4)(x^2-4x+16) d,(1/3x+2y)(1/9x^2-2/3xy+4y) e,(x-3y)(x2+3xy+9y^2)
\(1,A=\left(3x+7\right)\left(2x+3\right)-\left(2x+3\right)-\left(3x-5\right)\left(2x+11\right)\\ =6x^2+23x+21-2x-3-6x^2-23x+55\\ =73-2x\left(đề.sai\right)\\ B=x^4+x^3-x^2-2x^2-2x+2-x^4-x^3+3x^2+2x\\ =2\\ 2,\\ a,\Leftrightarrow30x^2+18x+3x-30x^2=7\\ \Leftrightarrow21x=7\Leftrightarrow x=\dfrac{1}{3}\\ b,\Leftrightarrow-63x^2+78x-15+63x^2+x-20=44\\ \Leftrightarrow79x=79\Leftrightarrow x=1\\ c,\Leftrightarrow\left(x+5\right)\left(x^2+3x+2\right)-x^3-8x^2=27\\ \Leftrightarrow x^3+3x^2+2x+5x^2+15x+10-x^3-8x^2=27\\ \Leftrightarrow17x=17\Leftrightarrow x=1\)
\(d,\Leftrightarrow7x-2x^2-3+x^2+x-6=-x^2-x+2\\ \Leftrightarrow9x=11\Leftrightarrow x=\dfrac{11}{9}\)
1, 7x+6(3-x)=27-20+73
2,6x-5(x-7)=(27-514)-486-73)
3,2x-6=3(x-5)+25+27-15-17
4, 4(x-5)-3(x+5)=2579-2578
5,/x-5/-7(x+4)=5-7x
6,3/x+4/-2(x-1)=7-2x
7, 2/x-6/+7x-2=/x-6/+7x
8,/x+8/+5(x-2)=5x-10:2
9, /x+2/-6(x-4)=20-6x
1: Ta có: 7x+6(3-x)=27-20+73
\(\Leftrightarrow7x+18-6x=80\)
\(\Leftrightarrow x=80-18=62\)
Vậy: x=62
2: Ta có: \(6x-5\left(x-7\right)=\left(27-514\right)-486-73\)
\(\Leftrightarrow6x-5x+35=27-514-486-73\)
\(\Leftrightarrow x+35=-1046\)
\(\Leftrightarrow x=-1081\)
Vậy: x=-1081
M.n ơi giúp e giải hộ câu này vs ạ !!
a) ( 3x-3 ).(5-21x)+ (7x+4).(9x-5) = 44
b) ( x+1).(x+2).(x+5)-x* . ( x+8) = 27
P/s : x* ( x bình phương hay x mũ 2 )
M.n giúp e sớm nha , mai e nộp bài r .
THANKS VERY MUCH =))
a) \(\Leftrightarrow\left(-63x^2+78x-15\right)+\left(63x^3+x-20\right)=44\)
\(\Leftrightarrow-63x^2+78x-15+63x^2+x-20=44\)
\(\Leftrightarrow79x-35=44\)
\(\Leftrightarrow79x=44+35\)
\(\Leftrightarrow79x=79\)
\(\Leftrightarrow x=1\)
b) \(\Leftrightarrow\left(x^2+3x+2\right).\left(x+5\right)-x^2.\left(x+8\right)=27\)
\(\Leftrightarrow x.\left(x^2+3x+2\right)+5.\left(x^2+3x+2\right)-x^3-8x^2=27\)
\(\Leftrightarrow x^3+3x^2+2x+5x^2+15x+10-x^3-8x^2=27\)
\(\Leftrightarrow17x+10=27\)
\(\Leftrightarrow17x=17\)
\(\Leftrightarrow x=1\)