Thu gọn
A=(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)(2^32+1)
rút gọnA=(2+1)*(2^2+1)(2^4+1)*(2^8+1)*(2^16+1)*(2^32+1)
Thu gọn
A=(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)(2^32+1)
+\(\left(a-b\right)\left(a+b\right)=a\left(a+b\right)-b\left(a+b\right)\)
\(=a^2+ab-ab-b^2=a^2-b^2\)
Do đó :\(A=\left(2-1\right)\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)+\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)\)\(A=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)\)
\(A=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)\)
\(A=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)\)
\(A=\left(2^{16}-1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)\)
\(A=\left(2^{32}-1\right)\left(2^{32}+1\right)=2^{64}-1\)
Thu gọn
a) \(\dfrac{1}{x-1}+\dfrac{2x}{x^2+x+1}=\dfrac{3x^2}{x^3-1}\)
b) \(\dfrac{x+2}{x-3}=\dfrac{x^2+3x}{x^2-9}\)
c) \(\dfrac{x-2}{x+2}-\dfrac{x+2}{x-2}=\dfrac{-16}{x^2-4}\)
Đây là bài giải pt chứ có phải biểu thức đâu mà thu gọn hả bạn?
Lời giải:
a. ĐKXĐ: $x\neq 1$
PT $\Leftrightarrow \frac{x^2+x+1}{(x-1)(x^2+x+1)}+\frac{2x(x-1)}{(x-1)(x^2+x+1)}=\frac{3x^2}{(x-1)(x^2+x+1)}$
$\Leftrightarrow x^2+x+1+2x(x-1)=3x^2$
$\Leftrightarrow 3x^2-x+1=3x^2$
$\Leftrightarrow x=1$ (không thỏa đkxđ)
Vậy pt vô nghiệm.
b. ĐKXĐ: $x\neq \pm 3$
PT $\Leftrightarrow \frac{(x+2)(x+3)}{(x-3)(x+3)}=\frac{x^2+3x}{(x-3)(x+3)}$
$\Leftrightarrow (x+2)(x+3)=x^2+3x$
$\Leftrightarrow x^2+5x+6=x^2+3x$
$\Leftrightarrow 2x+6=0$
$\Leftrightarrow x=-3$ (không thỏa mãn đkxđ)
Do đó pt vô nghiệm.
c. ĐKXĐ: $x\neq \pm 2$
PT $\Leftrightarrow \frac{(x-2)^2-(x+2)^2}{(x+2)(x-2)}=\frac{-16}{(x-2)(x+2)}$
$\Leftrightarrow (x-2)^2-(x+2)^2=-16$
$\Leftrightarrow -8x=-16$
$\Leftrightarrow x=2$ (vi phạm đkxđ)
Do đó pt vô nghiệm.
bài tập, rút gọn
a, √8-2√7 + √16-6√7
b, √(√7-1)2 - √11+4√7
c.ơn các bạn trước
`a)sqrt{8-2sqrt7}+sqrt{16-6sqrt7}`
`=sqrt{(sqrt7-1)^2}+sqrt{(3-sqrt7)^2}`
`=sqrt7-1+3-sqrt7=2`
`b)sqrt{(sqrt7-1)^2}-sqrt{11+4sqrt7}`
`=sqrt7-1-sqrt{(2+sqrt7)^2}`
`=sqrt7-1-2-sqrt7=-3`
a, \(=\sqrt{7-2\sqrt{7}+1}+\sqrt{7-2.3\sqrt{7}+9}\)
\(=\sqrt{\left(\sqrt{7}-1\right)^2}+\sqrt{\left(3-\sqrt{7}\right)^2}=\left|\sqrt{7}-1\right|+\left|3-\sqrt{7}\right|\)
\(=\sqrt{7}-1+3-\sqrt{7}=2\)
\(b,=\left|\sqrt{7}-1\right|-\sqrt{7+2.2\sqrt{7}+4}\)
\(=\left|\sqrt{7}-1\right|-\sqrt{\left(\sqrt{7}+2\right)^2}=\left|\sqrt{7}-1\right|-\left|\sqrt{7}+2\right|\)
\(=\sqrt{7}-1-\sqrt{7}-2=-3\)
a \(\Rightarrow\sqrt{7-2\sqrt{7}+1}+\sqrt{9-6\sqrt{7}+7}=\sqrt{\left(\sqrt{7}-1\right)^2}+\sqrt{\left(3-\sqrt{7}\right)^2}=\sqrt{7}-1+3-\sqrt{7}=2\) b \(\Rightarrow\sqrt{7}-1-\sqrt{7-4\sqrt{7}+4}=\sqrt{7}-1-\sqrt{\left(\sqrt{7}-2\right)^2}=\sqrt{7}-1-\sqrt{7}+2=1\)
Bài 1. Rút gọn
a. \(2\sqrt{8}-3\sqrt{18}+\sqrt{32}\)
b. \(\sqrt{\left(1-\sqrt{2}\right)^2}+\sqrt{\left(1+\sqrt{2}\right)^2}\)
c. \(\sqrt{\left(2-\sqrt{3}\right)^2}+\sqrt{4-2\sqrt{3}}\)
d. \(\sqrt{2-\sqrt{3}+\sqrt{2+\sqrt{3}}}\)
Bài 2. Giải phương trình
a. \(x\sqrt{8}-6\sqrt{2}=0\)
b. \(\sqrt{2x+1}-3=0\)
c. \(\sqrt{x^2-4x+4}-3=0\)
d. \(\sqrt{x-1}+\sqrt{4x-4}-\sqrt{25x-25+2}=0\)
a) Ta có: \(2\sqrt{8}-3\sqrt{18}+\sqrt{32}\)
\(=4\sqrt{2}-6\sqrt{2}+4\sqrt{2}\)
\(=2\sqrt{2}\)
b) Ta có: \(\sqrt{\left(1-\sqrt{2}\right)^2}+\sqrt{\left(1+\sqrt{2}\right)^2}\)
\(=\sqrt{2}-1+\sqrt{2}+1\)
\(=2\sqrt{2}\)
c) Ta có: \(\sqrt{\left(2-\sqrt{3}\right)^2}+\sqrt{4-2\sqrt{3}}\)
\(=2-\sqrt{3}+\sqrt{3}-1\)
=1
a) Ta có: 2√8−3√18+√3228−318+32
=4√2−6√2+4√2=42−62+42
=2√2=22
b) Ta có: √(1−√2)2+√(1+√2)2(1−2)2+(1+2)2
=√2−1+√2+1=2−1+2+1
=2√2
1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32
Tính
1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32 = 56744
1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32 = 56744
#nhớ tk
1/1-x +1/1+x +2/1+x^2 +4/1+x^4 +8/1+x^8 +16/1+x^16 = 32/1-x^32 c/m
\(\dfrac{1}{1-x}+\dfrac{1}{1+x}+\dfrac{2}{1+x^2}+\dfrac{4}{1+x^4}+\dfrac{8}{1+x^8}+\dfrac{16}{1+x^{16}}\)
\(=\dfrac{1+x+1-x}{1-x^2}+\dfrac{2}{1+x^2}+\dfrac{4}{1+x^4}+\dfrac{8}{1+x^8}+\dfrac{16}{1+x^{16}}\)
\(=\dfrac{2+2x^2+2-2x^2}{1-x^4}+\dfrac{4}{1+x^4}+\dfrac{8}{1+x^8}+\dfrac{16}{1+x^{16}}\)
\(=\dfrac{4+4x^4+4-4x^4}{1-x^8}+\dfrac{8}{1+x^8}+\dfrac{16}{1+x^{16}}\)
\(=\dfrac{8+8x^8+8-8x^8}{1-x^{16}}+\dfrac{16}{1+x^{16}}\)
\(=\dfrac{16+16x^{16}+16-16x^{16}}{1-x^{32}}=\dfrac{32}{1-x^{32}}\)
(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)=2^32-1
VT=[(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)]/2
=[(2^2-1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)]/2
=[(2^4-1(2^4+1)(2^8+1)(2^16+1)]/2
=[(2^8-1)(2^8+1)(2^16+1)]/2
=[(2^16-1)(2^16+1)]/2
=(2^32-1)/2
(2+1)(2^2+1)(2^4 +1)(2^8+1)(2^16+1) - 2^32 = ?
(2+1)(2^2+1)(2^4 +1)(2^8+1)(2^16+1) - 2^32
=1.(2+1)(22+1)(24 +1)(28+1)(216+1) - 232
=(2-1).(2+1)(22+1)(24 +1)(28+1)(216+1) - 232
=(22-1)(22+1)(24 +1)(28+1)(216+1) - 232
=(24-1)(24 +1)(28+1)(216+1) - 232
=(28-1)(28+1)(216+1) - 232
=(216-1)(216+1) - 232
=232-1-232
=-1
(2+1 ) ( 2^2 + 1) ... (2^16 + 1) - 2^32
= 3 ( 2^2 + 1) ....( 2^16 + 1) -2^32
= ( 2^2 - 1)( 2^2 +1)....(2^16 + 1 ) - 2^32
= (2^4 - 1)( 2^4 + 1)( 2^8 + 1)( 2^16 + 1) - 2^32
= ( 2^8 - 1) ( 2^8 + 1) ( 2^16 - 1 ) - 2^32
= ( 2^ 16 - 1) (2^16 + 1) - 2^32
= 2^32 - 1 - 2^32
=-1
tìm x biết:
câu a: (2x+1)-4(x+2)^2=9
câu b: (x+3)^2-(x-4)(x+8)=1
câu c: (x+1)^3 - (x-1)^3 - 6(x-1)^2=-19