tính:
1) (x+3)(x\(^2\) -3x+9) - x(x-2)(x+2)
2) (2a - b)(4a\(^2\) +2ab+b\(^2\) )
Những câu hỏi liên quan
C/m rằng
a) (a+3) .( a^2 -3a+9) - (54+x^3)
b) (2a+b) . (4a^2 -2ab +b^2 ) - (2a-b) . (4a^2+ +2ab +b^2)
c) (x +y)^2 - (x-y)^2
d) (x+y)^3 -( x-y)^3 -2y^3
rút gọn biểu thức:
A=(x +2)(x-4)+(x+1)(x-6)
B=(2a - b)(4a^2 + 2ab + b^2)
C=(2 + x)(2 - x)(x + 4)
a: Ta có: \(A=\left(x+2\right)\left(x-4\right)+\left(x+1\right)\left(x-6\right)\)
\(=x^2-4x+2x-8+x^2-6x+x-6\)
\(=2x^2-7x-14\)
b: \(B=\left(2a-b\right)\left(4a^2+2ab+b^2\right)=8a^3-b^3\)
c: \(C=\left(2+x\right)\left(2-x\right)\left(x+4\right)\)
\(=\left(4-x^2\right)\left(x+4\right)\)
\(=4x+16-x^3-4x^2\)
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1.Rút gọn biểu thức:(2x+3)2+(2x-3)2+2(2x+3)(2x-3)2.Thực hiện phép tính:a.(x2+xy+y2)(x-y)+(x2-xy+y2)(x+y)b.(2a-b).(4a2+2ab+b2)c.frac{1}{3}x.(3-x)-frac{1}{2}(x+1)d.(2x-1)(x+frac{1}{2})(x2+frac{1}{4})e.(2a-b).(4a2+2ab+b2)
Đọc tiếp
1.Rút gọn biểu thức:
(2x+3)2+(2x-3)2+2(2x+3)(2x-3)
2.Thực hiện phép tính:
a.(x2+xy+y2)(x-y)+(x2-xy+y2)(x+y)
b.(2a-b).(4a2+2ab+b2)
c.\(\frac{1}{3}\)x.(3-x)-\(\frac{1}{2}\)(x+1)
d.(2x-1)(x+\(\frac{1}{2}\))(x2+\(\frac{1}{4}\))
e.(2a-b).(4a2+2ab+b2)
thực hiện phép nhân
a)\(\text{ (x+1)(1+x−x^2+x^3−x^4)−(x−1)(1+x+x^2+x^3+x^4)}\)
B) \(\text{(2b^2−2−5b+6b^3)(3+3b^2−b)}\)
c) \(\text{(2ab+2a^2+b^2)(2ab^2+4a^3−4a^2b)}\)
d) \(\text{(2a^3−0,02a+0,4a^5)(0,5a^6−0,1a^2+0,03a^4)}\)
a: \(=x^5+1-x^5+1=2\)
b: \(=\left(6b^3+2b^2-5b-2\right)\left(3b^2-b+3\right)\)
\(=18b^5-6b^4+18b^3+6b^4-2b^3+6b^2-15b^3+5b^2-15b-6b^2+2b-6\)
\(=18b^5+b^3+5b^2-13b-6\)
c: \(=\left(2a^2+2ab+b^2\right)\cdot2a\left(b^2+2a^2-2ab\right)\)
\(=2a\left[\left(2a^2+b^2\right)^2-4a^2b^2\right]\)
\(=2a\left(4a^4+b^4\right)=8a^5+2ab^4\)
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1.Rút gọn biểu thức:
(2x+3)2+(2x-3)2+2(2x+3)(2x-3)
2.Thực hiện phép tính:
a.(x2+xy+y2)(x-y)+(x2-xy+y2)(x+y)
b.(2a-b).(4a2+2ab+b2)
c.13 x.(3-x)-12 (x+1)
d.(2x-1)(x+12 )(x2+14 )
e.(2a-b).(4a2+2ab+b2)
Bài 1:
\(\left(2x+3\right)^2+\left(2x-3\right)^2+2\left(2x+3\right)\left(2x-3\right)\)
\(=\left(2x+3+2x-3\right)^2=\left(4x\right)^2=16x^2\)
Bài 2:
a, \(\left(x^2+xy+y^2\right)\left(x-y\right)+\left(x^2-xy+y^2\right)\left(x+y\right)\)
\(=x^3-y^3+x^3+y^3=2x^3\)
b, \(\left(2a-b\right)\left(4a^2+2ab+b^2\right)\)
\(=\left(2a\right)^3-b^3=8a^3-b^3\)
c, \(13x\left(3-x\right)-12\left(x+1\right)\)
\(=39x-13x^2-12x-12=-13x^2-27x-12\)
d, \(\left(2x-1\right)\left(x+12\right)\left(x^2+14\right)\)
\(=\left(2x^2+24x-x-12\right)\left(x^2+14\right)\)
\(=2x^4+23x^3-12x^2+28x^2+322x-168\)
\(=2x^4+23x^3+16x^2+322x-168\)
e, Giống câu b
Chúc bạn học tốt!!!
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Tính
a) ( x -3)( 5x2 - 3x + 2)
b) ( 2a - b)( 4a2 + 2ab + b2)
a) \(\left(x-3\right)\left(5x^2-3x+2\right)=5x^3-3x^2+2x-15x^2+9x-6=5x^3-17x^2+11x-6\)
b) \(\left(2a-b\right)\left(4a^2+2ab+b^2\right)=8a^3-b^3\)
thực hiện phép nhân
a) \(\left(X+1\right)\left(1+X-X^2+X^3-X^4\right)-\left(X-1\right)\left(1+X+X^2+X^3+X^4\right)\)
B) \(\left(2b^2-2-5b+6b^3\right)\left(3+3b^2-b\right)\)
c) \(\left(2ab+2a^2+b^2\right)\left(2ab^2+4a^3-4a^2b\right)\)
d) \(\left(2a^3-0,02a+0,4a^5\right)\left(0,5a^6-0,1a^2+0,03a^4\right)\)
a)Adfrac{1}{2a-1}sqrt{5a^2left(1-4a+4a^2right)} với adfrac{1}{2} b)Adfrac{sqrt{x-2sqrt{x-1}}}{sqrt{x-1}-1}+dfrac{sqrt{x+2sqrt{x-1}}}{sqrt{x-1+1}} với x2 c)dfrac{a+b}{b^2}sqrt{dfrac{a^2b^4}{a^2+2ab+b^2}} với a+b0; b≠0d)Aleft(sqrt{dfrac{1-asqrt{a}}{1-sqrt{a}}}+sqrt{a}right)left(dfrac{1-sqrt{a}}{1-a}right)^2 với a≥0; a≠1e)Adfrac{x-1}{sqrt{y}-1}sqrt{dfrac{left(y-2sqrt{y}+1right)}{left(x-1right)^4}} với x≠1; y≠1; yof)Asqrt{dfrac{m}{1-2x+x^2}}sqrt{dfrac{4m-8mx+4mx^2}{81}} với m0; x≠4g)Aleft(dfrac{...
Đọc tiếp
a)A=\(\dfrac{1}{2a-1}\sqrt{5a^2\left(1-4a+4a^2\right)}\) với a>\(\dfrac{1}{2}\)
b)A=\(\dfrac{\sqrt{x-2\sqrt{x-1}}}{\sqrt{x-1}-1}\)+\(\dfrac{\sqrt{x+2\sqrt{x-1}}}{\sqrt{x-1+1}}\) với x>2
c)\(\dfrac{a+b}{b^2}\)\(\sqrt{\dfrac{a^2b^4}{a^2+2ab+b^2}}\) với a+b>0; b≠0
d)A=\(\left(\sqrt{\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}}+\sqrt{a}\right)\left(\dfrac{1-\sqrt{a}}{1-a}\right)^2\) với a≥0; a≠1
e)A=\(\dfrac{x-1}{\sqrt{y}-1}\sqrt{\dfrac{\left(y-2\sqrt{y}+1\right)}{\left(x-1\right)^4}}\) với x≠1; y≠1; y>o
f)A=\(\sqrt{\dfrac{m}{1-2x+x^2}}\)\(\sqrt{\dfrac{4m-8mx+4mx^2}{81}}\) với m>0; x≠4
g)A=\(\left(\dfrac{\sqrt{x}+1}{x-4}-\dfrac{\sqrt{x}-1}{x+4\sqrt{x}+4}\right)\)\(\dfrac{x\sqrt{x}+2x-4\sqrt{x}-8}{\sqrt{x}}\) với x>0; x≠4
h)\(\left(\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}\right)\)\(\left(\dfrac{1-\sqrt{a}}{1-a}\right)^2\) với a≥0; a≠1
a: \(A=\dfrac{1}{2a-1}\cdot\sqrt{5a^2}\cdot\left|2a-1\right|\)
\(=\dfrac{2a-1}{2a-1}\cdot a\sqrt{5}=a\sqrt{5}\)(do a>1/2)
b: \(A=\dfrac{\sqrt{x-1-2\sqrt{x-1}+1}}{\sqrt{x-1}-1}+\dfrac{\sqrt{x-1+2\sqrt{x-1}+1}}{\sqrt{x-1}+1}\)
\(=\dfrac{\left|\sqrt{x-1}-1\right|}{\sqrt{x-1}-1}+\dfrac{\sqrt{x-1}+1}{\sqrt{x-1}+1}\)
\(=\dfrac{\sqrt{x-1}-1}{\sqrt{x-1}-1}+1=1+1=2\)
c:
\(=\dfrac{a+b}{b^2}\cdot\dfrac{ab^2}{a+b}=a\)
d: Sửa đề: \(A=\left(\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}\right)\left(\dfrac{1-\sqrt{a}}{1-a}\right)^2\)
\(=\left(1+\sqrt{a}+a+\sqrt{a}\right)\cdot\left(\dfrac{1}{1+\sqrt{a}}\right)^2\)
\(=\dfrac{\left(\sqrt{a}+1\right)^2}{\left(\sqrt{a}+1\right)^2}=1\)
e:
\(A=\dfrac{x-1}{\sqrt{y}-1}\cdot\sqrt{\dfrac{\left(\sqrt{y}-1\right)^2}{\left(x-1\right)^4}}\)
\(=\dfrac{x-1}{\sqrt{y}-1}\cdot\dfrac{\sqrt{y}-1}{\left(x-1\right)^2}=\dfrac{1}{x-1}\)
f:
\(A=\sqrt{\dfrac{m}{\left(1-x\right)^2}\cdot\dfrac{4m\left(1-2x+x^2\right)}{81}}\)
\(=\sqrt{\dfrac{m}{\left(x-1\right)^2}\cdot\dfrac{4m\left(x-1\right)^2}{81}}\)
\(=\sqrt{\dfrac{4m^2}{81}}=\dfrac{2m}{9}\)
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Thu gọn các biểu thức sau:
a) (x+y)3 - (x-y)3 - 2y3
b) (x+2).(x2 - 2x+4) - (16-x3)
c) (2a+b). (4a2 - 4ab +b2) - (2a- b).(4a2+2ab+b2)
a/ (x+y)3-(x-y)3-2y3= (x3+3x2y+3xy2+y3)-(x3-3x2y+3xy2-y3)-2y3= x3+3x2y+3xy2+y3-x3+3x2y-3xy2+y3-2y3= 6xy2b/ (x+2)(x2-2x+4)-(16-x3)= x3-2x2+4x+2x2-4x+8-16+x3= 2x3-8c/ (2a+b)(4a2-2ab+b2)-(2a-b)(4a2+2ab+b2)= (8a3+b3)-(8a3-b3)= 8a3+b3-8a3+b3= 2b3
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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