A,3.x - 16 : 2^3= 31; B,2^10 : 2^8 + 3. [4. 7 + 3.4 ] ; C,4^6 : 4^3 - 2^2 . 2^3; D,141 + 2^5 . 2^4 - 3^1 . 3^2 ; E,x + 2^5 : 2^4 = 4.4^2 giúp mình với
Những câu hỏi liên quan
cho hsố:f(x)=(x2+12x-31)
Tính P(a)tại a=\(\sqrt[3]{16-8\sqrt{5}}+\sqrt[3]{16+8\sqrt{5}}\)
\(a=\sqrt[3]{16-8\sqrt{5}}+\sqrt[3]{16+8\sqrt{5}}\)
\(\Leftrightarrow a^3=16-8\sqrt{5}+16+8\sqrt{5}+3\sqrt[3]{\left(16-8\sqrt{5}\right)\left(16+8\sqrt{5}\right)}\cdot a\)
\(\Leftrightarrow a^3=32+3\sqrt[3]{256-320}\cdot a\)
\(\Leftrightarrow a^3=32-12a\)
Giải pt được \(a=2\).
Khi đó : \(P\left(a\right)=\left(2^2+12\cdot2-31\right)=-3\)
Vậy...
Đúng 0
Bình luận (0)
Bài 1
a. -25 . 21.(-2)2.(-|-3|) .(-1)2n ( n ∈ N sao)
b. 35.18-5.7.18
c. 24 . (16-5) -16.(24-5)
d.29 . (19-13) - 19 . (29-13)
e. -48 .(-78) +48 . (-21)
f. 31.(-18)+31.(-18) -31
Bài 2 : Tính tổng:
a. 1+(-2)+3+(-4)+........+19+(-20)
b. 2-4+6-8+...+48-50
c. 1+2-3-4+.....+97+98-99-100
Bài 3: Tìm x
a. -2x - (x -17) 34 - (-x +25)
b. 17.x+(16.x-37) 2x +43
c. |2.x+1| -19 -7
d. 12-2.(-x+3)2 -38
e. -20+3.(2x+1)3 -101
Đọc tiếp
Bài 1
a. -25 . 21.(-2)2.(-|-3|) .(-1)2n ( n ∈ N sao)
b. 35.18-5.7.18
c. 24 . (16-5) -16.(24-5)
d.29 . (19-13) - 19 . (29-13)
e. -48 .(-78) +48 . (-21)
f. 31.(-18)+31.(-18) -31
Bài 2 : Tính tổng:
a. 1+(-2)+3+(-4)+........+19+(-20)
b. 2-4+6-8+...+48-50
c. 1+2-3-4+.....+97+98-99-100
Bài 3: Tìm x
a. -2x - (x -17) = 34 - (-x +25)
b. 17.x+(16.x-37) = 2x +43
c. |2.x+1| -19 = -7
d. 12-2.(-x+3)2= -38
e. -20+3.(2x+1)3= -101
a, 6.(x-1)-5x=15
b, 2.(4x-2)-7x=16
c,-2.(-3-4x)-3.(3x-7)=31
a) => 6x-6-5x=15
=> 6x-6+6-5x=15+6
=> 6x-5x=21
=> x=21
b) => 8x-4-7x=16
=> 8x-4+4-7x=16+4
=> 8x-7x=20
=> x=20
c) => 8-[-(2.4x)]-9x-21=31
=> 8-(-8x)-9x=31+21
=> 8-(-8x)-9x=52
=> (-8x)-9x=8-52
=> (-8x)+(-9x)=-44
=> -17x=-44
=> x=(-44):(-17)
=> x=
câu c chắc tớ làm sai
Đúng 0
Bình luận (0)
a) 6*(x-1)-5x=15
b) -2*(-3-4x)-3*(3x-7)=31
c) 2*(4x-2)-7x=16
a, -15/16 + 9/16 + 11/16
b, 2/3 . (1,4) + 1,6 . 2/3 - 1,2 . 2/3
c, 3 và 2/15. 3/5+ 3 và 2/15. 2/5- 31/15
a) \(\dfrac{-15+9+11}{16}=\dfrac{5}{16}\)
b) \(\dfrac{2}{3}\left(1,4+1,6-1,2\right)=\dfrac{2}{3}\times\dfrac{9}{5}=\dfrac{6}{5}\)
c) \(3\dfrac{2}{15}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)-\dfrac{31}{15}=\dfrac{47}{15}-\dfrac{31}{15}=\dfrac{16}{15}\)
Đúng 1
Bình luận (0)
bài 1 : tìm x a, 1/551/2 b, 11/5+x9c,5-x7/17 d, x-1/316/5:3/2e,8/9:x11/2 g, x:31/52+7/2 h,7/8x íc29/2-2 giải hết ra cho mink nha
Đọc tiếp
bài 1 : tìm x
a, 1/5=5=1/2 b, 11/5+x=9
c,5-x=7/17 d, x-1/3=16/5:3/2
e,8/9:x=11/2 g, x:31/5=2+7/2
h,7/8x íc=29/2-2
giải hết ra cho mink nha
a)dfrac{2}{3}x-1dfrac{3}{2}b)| 5x - dfrac{1}{2}| - dfrac{2}{7} 25%c)dfrac{x-3}{4}dfrac{16}{x-3}d)dfrac{-8}{13}+dfrac{7}{17}+dfrac{21}{31}x≤dfrac{-9}{14}+4+dfrac{5}{-14}(xϵZ)
Đọc tiếp
a)\(\dfrac{2}{3}\)x-1=\(\dfrac{3}{2}\)
b)| 5x - \(\dfrac{1}{2}\)| - \(\dfrac{2}{7}\)= 25%
c)\(\dfrac{x-3}{4}\)=\(\dfrac{16}{x-3}\)
d)\(\dfrac{-8}{13}\)+\(\dfrac{7}{17}+\dfrac{21}{31}\)<x≤\(\dfrac{-9}{14}\)+4+\(\dfrac{5}{-14}\)(xϵZ)
a) Ta có: \(\dfrac{2}{3}x-1=\dfrac{3}{2}\)
\(\Leftrightarrow x\cdot\dfrac{2}{3}=\dfrac{5}{2}\)
hay \(x=\dfrac{5}{2}:\dfrac{2}{3}=\dfrac{5}{2}\cdot\dfrac{3}{2}=\dfrac{15}{4}\)
b) Ta có: \(\left|5x-\dfrac{1}{2}\right|-\dfrac{2}{7}=25\%\)
\(\Leftrightarrow\left|5x-\dfrac{1}{2}\right|=\dfrac{1}{4}+\dfrac{2}{7}=\dfrac{15}{28}\)
\(\Leftrightarrow\left[{}\begin{matrix}5x-\dfrac{1}{2}=\dfrac{15}{28}\\5x-\dfrac{1}{2}=\dfrac{-15}{28}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=\dfrac{29}{28}\\5x=\dfrac{-1}{28}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{29}{140}\\x=\dfrac{-1}{140}\end{matrix}\right.\)
Đúng 0
Bình luận (0)
c) Ta có: \(\dfrac{x-3}{4}=\dfrac{16}{x-3}\)
\(\Leftrightarrow\left(x-3\right)^2=64\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=8\\x-3=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=11\\x=-5\end{matrix}\right.\)
d) Ta có: \(\dfrac{-8}{13}+\dfrac{7}{17}+\dfrac{21}{31}\le x\le\dfrac{-9}{14}+4-\dfrac{5}{14}\)
\(\Leftrightarrow\dfrac{3246}{6851}\le x\le3\)
\(\Leftrightarrow x\in\left\{1;2;3\right\}\)
Đúng 0
Bình luận (0)
96/x^2-16+7+x/4-x=2x-1/x+4-3
2/x-1 +3/x-2 =3/x-3
1/x+1+5-x/x-2=3/x^2-x-2-1
a: \(\dfrac{96}{\left(x-4\right)\left(x+4\right)}+\dfrac{7+x}{4-x}=\dfrac{2x-1}{x+4}-3\)
\(\Leftrightarrow\dfrac{96}{\left(x-4\right)\left(x+4\right)}-\dfrac{\left(x+7\right)\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{\left(2x-1\right)\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}-\dfrac{3\left(x-4\right)\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}\)
Suy ra: \(96-x^2-11x-28=2x^2-9x+4-3\left(x^2-16\right)\)
\(\Leftrightarrow-x^2-11x+68=2x^2-9x+4-3x^2+48\)
\(\Leftrightarrow-x^2-11x+68=-x^2-9x+52\)
=>-11x+68=-9x+52
=>-2x=-16
hay x=8(nhận)
b: \(\dfrac{2}{x-1}+\dfrac{3}{x-2}=\dfrac{3}{x-3}\)
\(\Leftrightarrow2\left(x-2\right)\left(x-3\right)+3\left(x-1\right)\left(x-3\right)=3\left(x-1\right)\left(x-2\right)\)
\(\Leftrightarrow2\left(x^2-5x+6\right)+3\left(x^2-4x+3\right)=3\left(x^2-3x+2\right)\)
\(\Leftrightarrow2x^2-10x+12+3x^2-12x+9=3x^2-9x+6\)
\(\Leftrightarrow5x^2-22x+21-3x^2+9x-6=0\)
\(\Leftrightarrow2x^2-13x+15=0\)
\(\Leftrightarrow2x^2-10x-3x+15=0\)
=>(x-5)(2x-3)=0
=>x=5(nhận) hoặc x=3/2(nhận)
Đúng 3
Bình luận (0)
-4(5-x)=-3(6-x)
-3(x-8)-(2x-7)=35
2. Tính tổng
1+(-2)+3+(-4)+...+49+(-50)
1-2+3-4+...+99-100
2-4+6-8+...+49-50
Tính hợp lý
24(16-5)-16(24-5)
29-(19-13)-19(29*13)
31*(-18)+31*(-81)-31
(-12)*47+(-12)*52+(-12)
13(23+22)-3(17+28)
