Giúp mik với ạ!! mik đang cần gấp
Cho x+y=7, x.y= 6. Tính giá trị các biểu thức sau:
a, \(\dfrac{2}{x}\)+ \(\dfrac{2}{y}\) b, x2+y2 -2xy
c,x3 + y3 d, \(\dfrac{x^2+y^2}{\left|x-y\right|}\)
bài trên thấy làm ròi
You always go to bed at 9 o'clock
We usually go to the cinema on Wednesday
I often read a magazine on Sunday morning
She never eats fish
He always does his homework on Fridays
2. You always go to bed at 6 o'clock.
3. We usually go to the cinema on Wed.
4. I often read a magazine on Sun morning.
5. She never eats fish.
6. He always does his HW on Fri.
tên ngày mik ziết tắt nha :))
a: \(=7^8\)
b: \(=3^{16}\)
c: \(=\left(-6\right)^6=6^6\)
d: \(=\left(-2\right)^{11}\)
e: \(=\left(-0.1\right)^5\)
f: \(=\left(\dfrac{4}{5}\right)^7\)
`7^3*7^5=7^{3+5}=7^8`
`3^7*3^9=3^{7+9}=3^16`
`(-6)^5*(-6)=(-6)^6`
`(-2)^5*(-2)^6=(-2)^{5+6}=(-2)^{11}`
`(-0,1)^2*(-0,1)^3=(-0,1)^{2+3}=(-0,1)^6`
Các câu còn lại tương tự nhé
a: A=-2/5+2/5+3/4-3/4+6/7=6/7
b: A=-1/8-7/8+7/9+6/7+1/7
=7/9
c: A=2/3+2/7=20/21
e: \(=\dfrac{4\cdot13-4\cdot40}{3\cdot9}=\dfrac{4\cdot\left(-27\right)}{-27}=-4\)
`A = -2/5 + 3/(-4) + 6/7 + 3/4 + 2/5`
`A= (-2/5+2/5)+(3/(-4) + 3/4) + 6/7`
`A = 0+0+6/7`
`A=6/7`
________________________
`B=-1/8 + 7/9 + 7/(-8) + 6/7 + 2/14`
`B = (-1/8 + 7/(-8)) + (6/7 + 2/14) + 7/9`
`B = -1 + 1 + 7/9`
`B = 0+ 7/9`
`B =7/9`
_________________________________________
`A = 2/3 + 1/5 . 10/7`
`A = 2/3 + (1xx10)/(5xx7)`
`A = 2/3 + 57/35`
`A= 241/105`
___________________________
`B = 7/12 - 27/7 . 1/18`
`B = 7/12 - (27.1)/(7.18)`
`B=7/12- 3/14`
`B= 31/84`
__________________________
`4/9 . 13/3 - 4/3 . 40/9`
`=(4.13)/(9.3) - (4.40)/(3.9)`
`=(4.13-4.40)/(9.3)`
`=(4.(13-40))/27`
`=(4.(-27))/27`
`=-4`
____________________________________
`M=1/(3.5) + 1/(5.7) + 1/(7.9) + .... +1/(97.99)`
`M = 1/2 . (2/(3.5) + 2/(5.7) + 2/(7.9) + .... +2/(97.99))`
`M = 1/2 . (1/3 - 1/5 + 1/5 - 1/7 + ...... + 1/97 - 1/99)`
`M = 1/2 . (1/3 - 1/99)`
`M = 1/2 . 32/99`
`M= 16/99`
Áp dụng đl pytago đảo vào tg ABC
Ta thấy : \(BC=\sqrt{AB^2+AC^2}\)
\(50=\sqrt{48^2+14^2}\)
=> tg ABC vuông tại A
=> góc B + góc C = 90o ( phụ nhau )
=> \(sinB=cosC\)
=> góc C = 60o
=> phgiác góc C = 30o
Solar energy will be used by many countries in the world
How will you travel from one place to another
We will reduce the use of electricity to save our energy
There are always traffic jams during rush-hours
1 Solar enery will be used by many countries in the world
2 How will you travel from one place to another
3 We will reduce the use of electricity to save our energy
4 There are always traffic jam during rush-hours
Cái này có phải là
always: 100%
usually: 75%
often: 50%
sometimes:25%
never:0%
2 always
3 never
4 often
5 always
6 sometimes
7 usually
2 ALWAYS
3 never
4 often
5 always
6 sometimes
7 usually
always
never
often
always
sometimes
often
`a)`\(A=b^2-4ac\)
\(=\left[2\left(m-3\right)\right]^2-4.\left(-1\right).\left(m-5\right)\)
\(=4\left(m-3\right)^2+4\left(m-5\right)\)
\(=4\left(m^2-6m+9\right)+4\left(m-5\right)\)
\(=4m^2-24m+36+4m-20\)
\(=4m^2-20m+16\)
`b)`\(A=4m^2-20m+16\)
\(=\left(2m\right)^2-2.2m.5+25-9\)
\(=\left(2m-5\right)^2-9\ge-9\)
( không lớn hơn `0` được á bạn )
a, \(A=4\left(m-3\right)^2+4\left(m-5\right)=4m^2-24m+36+4m-20=4m^2-20m+16\)
b, \(4\left(m^2-5m\right)+16=4\left(m^2-\dfrac{2.5}{2}m+\dfrac{25}{4}-\dfrac{25}{4}\right)+16\)
\(=4\left(m-\dfrac{5}{2}\right)^2-9\ge-9\)Vậy đpcm ko xảy ra