Bài 1: Rút gọn
A=(7-2x)(7+2x)+(2x+7)2
B=(4x-5)2-(2x-1)(8x-5)
C=(5x-3)2-2(5x-3)(5-5x)+(5x-5)2
D=(2a+3b-c)(2a-3b+c)-(4a2-9b2-c2)
Bài 1: Rút gọn
A=(7-2x)(7+2x)+(2x+7)2
B=(4x-5)2-(2x-1)(8x-5)
C=(5x-3)2-2(5x-3)(5-5x)+(5x-5)2
D=(2a+3b-c)(2a-3b+c)-(4a2-9b2-c2)
A=(7-2x)(7+2x)+(2x+7)2
=49-4x2+4x2+28x+49
= 98+28x
B=(4x-5)2-(2x-1)(8x-5)
= 16x2-25-((8x(2x-1))-(5(2x-1)))
= 16x2-25-((16x2+8x)-(10x+5))
= 16x2-25-(16x2+8x-10x-5)
= 16x2-25-16x2-8x+10x+5
= -20+2x
$\frac{4x+3}{5}$ -$\frac{6x-2}{7}$ =$\frac{5x+4}{3}$ +3
b.
$\frac{x+4}{5}$ -x+4=$\frac{x}{3}$ -$\frac{x-2}{2}$
c.$\frac{5x+2}{6}$ -$\frac{8x-1}{3}$ =$\frac{4x+2}{5}$ -5
d.$\frac{2x+3}{3}$ =$\frac{5-4}{2}$
e. $\frac{5x+3}{12}$ =$\frac{1+2x}{9}$
f.$\frac{7x-1}{6}$ =$\frac{16-x}{5}$
g. $\frac{x-3}{5}$ =6-$\frac{1-2x}{3}$
h. $\frac{3x-2}{6}$ -5=$\frac{3-2(x+7)}{4}$
giúp vs ạ, cần gấp
d: =>4x+6=15x-12
=>4x-15x=-12-6=-18
=>-11x=-18
hay x=18/11
e: =>\(45x+27=12+24x\)
=>21x=-15
hay x=-5/7
f: =>35x-5=96-6x
=>41x=101
hay x=101/41
g: =>3(x-3)=90-5(1-2x)
=>3x-9=90-5+10x
=>3x-9=10x+85
=>-7x=94
hay x=-94/7
Question Expandand simplify: 1. 8(x+5)-3(2x+7)
2. a(2b+c)+b(3c-2a)
3. 2y(y+5x)+x(3x+4y)
answer , 1. 8(x+5)-3(2x+7)=8x+40-6x+21=2x+61
2. a(2b+c)+b(3c-2a)=2ab+ac+3bc-2ab=ac+3bc=3abc^(2)
3. 2y(y+5x)+x(3x+4y)=2y^(2)+10xy+9x^(2)+4xy=9x^(2)+2y^(2)+14xy
a Explain what he has done wrong.
b work out the correct answer
Bài 3: Giải các phương trình sau bằng cách đưa về dạng ax +b =0
a)7 – x = -2x +3
b) 2 (3x +1) = -2x +5
c) 5x + 2(x – 1) = 4x + 7.
d) 10x^2 - 5x(2x + 3) = 15
\(\)
a, <=> x = -4
b, <=> 6x + 2 = -2x + 5 <=> 8x = 3 <=> x = 3/8
c, <=> 5x + 2x - 2 = 4x + 7 <=> 2x = 9 <=> x = 9 /2
d, <=> 10x^2 - 10x^2 - 15x = 15 <=> x = -1
a, <=> x = -4
b, <=> 6x + 2 = -2x + 5 <=> 8x = 3 <=> x = 3/8
c, <=> 5x + 2x - 2 = 4x + 7 <=> 2x = 9 <=> x = 9 /2
d <=> 10x^2 - 10x^2 - 15x = 15 <=> x = -1
a) x=-4
b)4x=3
x=3/4
c)3x=9
x=3
d) 15x=15
x=1
Bài 3: Giải các phương trình sau bằng cách đưa về dạng ax +b =0 ( giải chi tiết )
a)7 – x = -2x +3
b) 2 (3x +1) = -2x +5
c) 5x + 2(x – 1) = 4x + 7.
d) 10x^2 - 5x(2x + 3) = 15
a: =>-x+2x=3-7
=>x=-4
b: =>6x+2+2x-5=0
=>8x-3=0
hay x=3/8
c: =>5x+2x-2-4x-7=0
=>3x-9=0
hay x=3
d: =>10x2-10x2-15x=15
=>-15x=15
hay x=-1
C1) phân tích thành nhân tử
a) 4x^2 - 12xy + 9y^2
b) 27a^3 - 64b^3
c) (2a - 3b)(a + b )+ (5a - 2b)(3b - 2a) - (4a - 3b)^2
d) (2x - 6y)^2 - (3xy - 4)^2
C2) tìm x, biết
a) (2x - 3)^3 = (2x -9)(4x^2 +3)
b)(5x - 4) = (5x - 2)(5x + 2)
a) 4x^2 - 12xy + 9y^2
=(2x)^2 - 2.2.3xy + (3y)^2
=(2x+3y)^2
b) 27a^3 - 64b^3
=(3a)^3 - (4b)^3
=(3a - 4b) [(3a)^2 +3a.4b +(4B)^2]
d) (2x - 6y)^2 - (3xy - 4)^2
=[ (2x - 6y)+ (3xy - 4) ] [ (2x - 6y)- (3xy - 4) ]
\(1,a,4x^2-12xy+9y^2\)
\(=\left(2x\right)^2-2.3.2xy+\left(3y\right)^2\)
\(=\left(2x-3y\right)^2\)
\(b,27a^3-64b^3\)
\(=\left(3a\right)^3-\left(4b\right)^3\)
\(\left(3a-4b\right)\left(9a^2+12ab+16b^2\right)\)
Giải các phương trình sau:
a/ 3x – 2 = 2x – 3
b/ 7 – 2x = 22 – 3x
c) 8x – 3 = 5x + 12
d/ x – 12 + 4x = 25 + 2x – 1
e/ x + 2x + 3x – 19 = 3x + 5
a) \(PT\Leftrightarrow3x-2x=2-3\Leftrightarrow x=-1\)
Vậy: \(S=\left\{-1\right\}\)
b) \(PT\Leftrightarrow-2x+3x=-7+22\Leftrightarrow x=15\)
Vậy: \(S=\left\{15\right\}\)
c) \(PT\Leftrightarrow8x-5x=3+12\Leftrightarrow3x=15\Leftrightarrow x=5\)
Vậy: \(S=\left\{5\right\}\)
d) \(PT\Leftrightarrow x+4x-2x=12+25-1\Leftrightarrow3x=36\Leftrightarrow x=12\)
Vậy: \(S=\left\{12\right\}\)
e) \(PT\Leftrightarrow x+2x+3x-3x=19+5\Leftrightarrow3x=24\Leftrightarrow x=8\)
Vậy: \(S=\left\{8\right\}\)
a)3x-2=2x-3
=>x=-1
b)7-2x=22-3x
=>x=15
c)8x-3=5x+12
=>3x=15
=>x=5
d)x-12+4x=25+2x-1
=>3x=12
=>x=4
e)x+2x+3x-19=3x+5
=>3x=24
=>x=8
a)3x-2=2x-3
=>x=-1
b)7-2x=22-3x
=>x=15
c)8x-3=5x+12
=>3x=15
=>x=5
d)x-12+4x=25+2x-1
=>3x=36
=>x=12
e)x+2x+3x-19=3x+5
=>3x=24
=>x=8
Rút gọn:
a) A=(4-5x)2-(3+5x)2
b) B=(3x-1)(1+3x)-(3x+1)2
c) C=(2x+5)3-(2x-5)3-(120x2+49)
d) D=(2a-b+2)3-6(2a-b+2)2+12(2a-b+2)-8-(2a-b)3
a) A=(4-5x)2-(3+5x)2=(4-5x-3-5x)(4-5x+3+5x)=(-25x+1)1=-25x+1
B=(3x-1)(1+3x)-(3x+1)2=9x2-1-(3x+1)2=9x2-1-(9x2+6x+1)=9x2-1-9x2-6x-1=-6x-2=-2(3x+1)
Bài 1: Rút Gọn
a)(x+7)(x-7)-x2
b)(5x-1)(5x+1)-(25x2+1)
c)(4x+1)(4x-1)-(4x-1)2
d)(3x-5)2-(3x+5)(3x-5)
a) \(=x^2-49-x^2\) \(=-49\)
b) \(=25x^2-1-25x^2-1\) \(=-2\)
c) \(=16x^2-1-16x^2+8x-1\) \(=8x-2\)
d) \(=9x^2-30x+25-9x^2+25\) \(=50-30x\)