Rút gọn
( 1/4)44 x ( 1/2)12
317 x 8111 / 2710 x 915
915: 2710= bao nhiêu?
bài 1 rút gọn phân số sau
a -1/4+33/44
b -2/7+1/2+-3/4
Bai 2 tim x
1+-1/60+19/120<x/36<58/99+59/72+-1/60
1 a..Rút gọn biểu thức A = \(\dfrac{\text{ x 2 − 4 x + 4}}{\text{x 3 − 2 x 2 − ( 4 x − 8 ) }}\)
b. Rút gọn biểu thức B = \(\left(\dfrac{x+2}{\text{x }\sqrt{\text{x }}+1}-\dfrac{1}{\sqrt{\text{x}}+1}\right).\dfrac{\text{4 }\sqrt{x}}{3}\)
a.\(A=\dfrac{x^2-4x+4}{x^3-2x^2-\left(4x-8\right)}=\dfrac{\left(x-2\right)^2}{x^2\left(x-2\right)-4\left(x-2\right)}=\dfrac{\left(x-2\right)^2}{\left(x^2-4\right)\left(x-2\right)}=\dfrac{x-2}{\left(x-2\right)\left(x+2\right)}=\dfrac{1}{x+2}\)
\(A=\dfrac{\left(x-2\right)^2}{x^2\left(x-2\right)-4\left(x-2\right)}\left(x\ne\pm2\right)\\ A=\dfrac{\left(x-2\right)^2}{\left(x-2\right)^2\left(x+2\right)}=\dfrac{1}{x+2}\\ B=\dfrac{x+2-x+\sqrt{x}-1}{\left(\sqrt{x}+1\right)\left(x-\sqrt{x}+1\right)}\cdot\dfrac{4\sqrt{x}}{3}\left(x>0\right)\\ B=\dfrac{4\sqrt{x}\left(\sqrt{x}+1\right)}{3\left(\sqrt{x}+1\right)\left(x-\sqrt{x}+1\right)}=\dfrac{4\sqrt{x}}{3\left(x-\sqrt{x}+1\right)}\)
bài 1 rút gọn biểu thức
a) (2x-5)^2-4x(x+3)
b) (x-2)^3 -6(x+4)(x-4)-(x-2)(x^2+2x+4)
c)(x-1)^2-2(x-1)(x+2)+(x+2)^2+5(2x-3)
bài 2 rút gọn biểu thức
a)(2-3x)^2-5x(x-4)+4(x-1)
b)(3-x)(x^2+3x+9)+(x-3)^3
c)(x-4)^2(x+4)-(x-4)(x+4)^2+3(x^2-16)
1:
a: \(\left(2x-5\right)^2-4x\left(x+3\right)\)
\(=4x^2-20x+25-4x^2-12x\)
=-32x+25
b: \(\left(x-2\right)^3-6\left(x+4\right)\left(x-4\right)-\left(x-2\right)\left(x^2+2x+4\right)\)
\(=x^3-6x^2+12x-8-\left(x^3-8\right)-6\left(x^2-16\right)\)
\(=-6x^2+12x-6x^2+96=-12x^2+12x+96\)
c: \(\left(x-1\right)^2-2\left(x-1\right)\left(x+2\right)+\left(x+2\right)^2+5\left(2x-3\right)\)
\(=\left(x-1-x-2\right)^2+5\left(2x-3\right)\)
\(=\left(-3\right)^2+5\left(2x-3\right)\)
\(=9+10x-15=10x-6\)
2:
a: \(\left(2-3x\right)^2-5x\left(x-4\right)+4\left(x-1\right)\)
\(=9x^2-12x+4-5x^2+20x+4x-4\)
\(=4x^2+12x\)
b: \(\left(3-x\right)\left(x^2+3x+9\right)+\left(x-3\right)^3\)
\(=27-x^3+x^3-9x^2+27x-27\)
\(=-9x^2+27x\)
c: \(\left(x-4\right)^2\left(x+4\right)-\left(x-4\right)\left(x+4\right)^2+3\left(x^2-16\right)\)
\(=\left(x-4\right)\left(x+4\right)\left(x-4-x-4\right)+3\left(x^2-16\right)\)
\(=\left(x^2-16\right)\left(-8\right)+3\left(x^2-16\right)\)
\(=-5\left(x^2-16\right)=-5x^2+80\)
rút gọn biểu thức x(x+4)(x-4)-(x^2+1)(x^2-1)
x(x+4)(x-4)-(x^2+1)(x^2-1)=x(x2-16)-(x4-1)
=x3-16x-x4+1
T=2(x-1)/√x+1 + x-4/√x-2 Rút gọn Tính t khi x=4
\(T=\dfrac{2\left(x-1\right)}{\sqrt{x}+1}+\dfrac{x-4}{\sqrt{x}-2}\)
\(T=\dfrac{2\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}{\sqrt{x}-1}+\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}{\sqrt{x}-2}\)
\(T=2\left(\sqrt{x}+1\right)+\left(\sqrt{x}+2\right)\)
\(T=2\sqrt{x}+2+\sqrt{x}+2\)
\(T=3\sqrt{x}+4\)
\(x=4\)
\(\Rightarrow T=3\sqrt{4}+4=3.2+4=10\)
ta có:
rút gọn (x+2)^2 - (x+4)(x+1)
`(x+2)^2-(x+4)(x+1)`
`=x^2 +2*x*2+2^2 - (x^2+x+4x+4)`
`=x^2+4x+4-x^2-x-4x-4`
`= (x^2-x^2)+(4x-x-4x)+(4-4)`
`= -x`
Rút gọn: x.( x - 4).(x+4) - (x2+1).(x2-1)