2/x-1/3/-4=-1 tính xem bằng mấy tớ tích cho
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a) \(x\left(x+4\right)\left(x-4\right)-\left(x^2-1\right)\left(x^2+1\right)\)
\(=x\left(x^2-16\right)-\left(x^4-1\right)\)
\(=x^3-16x-x^4+1\)
bạn ktra lại đề
b) \(x^4+2x^3+5x^2+4x-12\)
\(=x^3\left(x-1\right)+3x^2\left(x-1\right)+8x\left(x-1\right)+12\left(x-1\right)\)
\(=\left(x-1\right)\left(x^3+3x^2+8x+12\right)\)
\(=\left(x-1\right)\left[x^2\left(x+2\right)+x\left(x+2\right)+6\left(x+2\right)\right]\)
\(=\left(x-1\right)\left(x+2\right)\left(x^2+x+6\right)\)
Câu 2:
Ta thấy:
$\frac{S_{BDM}}{S_{CDM}}=\frac{AB}{CD}=\frac{1}{3}$ (chung cạnh đáy $DM$)
Lại có:
$S_{ABD}=\frac{AB\times AD}{2}$
$S_{ABCD}=\frac{(AB+CD)\times AD}{2}=\frac{(AB+3\times AB)\times AD}{2}=\frac{4\times AB\times AD}{2}$
Suy ra $\frac{S_{ABD}}{S_{ABCD}}=\frac{1}{4}$
Suy ra $S_{ABD}=\frac{1}{4}\times S_{ABCD}=\frac{1}{4}\times 16=4$ (cm2)
$S_{BCD}=S_{ABCD}-S_{ABD}=16-4=12$ (cm2)
Hai tam giác $BDM$ và $CDM$ có tỉ số diện tích là $\frac{1}{3}$, hiệu diện tích là $S_{BCD}=12$ cm2 nên diện tích tam giác $BDM$ là:
$S_{BDM}=12:(3-1)\times 1=6$ (cm2)
$S_{ABM}=S_{BDM}-S_{BAD}=6-4=2$ (cm2)
Câu 1:
$(x+1)+(x+3)+(x+5)=30$
$x+1+x+3+x+5=30$
$(x+x+x)+(1+3+5)=30$
$3\times x+9=30$
$3\times x=30-9=21$
$x=21:3$
$x=7$
4x+4x+2=272
4x+4x.42=272
4x.1+4x.16=272
4x.(16+1)=272
4x.17=272
4x=272:17
4x=16=42
=>x=2
\(x^{50}=x\)
\(=>x\in\left\{1;0\right\}\)
\(\left(2^x+1\right)^3=125\)
\(\left(2^x+1\right)^3=5^3\)
\(2^x+1=5\)
\(2^x=4\)
\(2^x=2^2\)
\(=>x=2\)
Ex 2 :
1) What time is it? - It's 8 o'clock right now. 2) What time do you go to school? – I go to school at 6:45. 3) She watches TV at 7 pm. 4) She goes to bed at 9:30 pm. 5) They play soccer in the afternoon. 6) Where were you yesterday? – I was at the zoo. 7) What did you do last Sunday morning? - I watered the flowers in the garden. 8) Linda has breakfast at 6:30. 9) My mother wakes up early in the morning. 10) What time does your father go to work? – He goes to work at 7:10. 11) What do you do in the afternoon? – I do my homework.
1. What time ………is…………. it? -It………is………….9 o’clock./ ………It is…………. 10:30.
2. What ………time………….is it? - It………is…………. Ten twelve./ …It is ………………. 10:30.
3. What time ……are……………you get up? - I get up ……at……………. six o’clock.
4. ………When…………. do you go to school? - I go ………to school…………. At sixthirty.
5. What …………time………. do you have lunch? - I have lunch ……around……………. twelve o’clock.
6. What time …………does………. she/ he get up? - He/ She ………get…………. up at six o’clock.
S = 1+1/2.(1+2)+1/3.(1+2+3)+...+1/100.(1+2+3+...+100)
= 1+1/3.(1+2+3)+1/5.(1+2+3+4+5)+...+1/99(1+2+3+...+99) + 1/2.(1+2)+1/4.(1+2+3+4)+...+1/100.(1+2+3+...+100)
= (1+2+3+...+50)+(3/2+5/2+7/2+...+101/2)
= 1275+1300
= 2575
Ý bạn là vầy chứ gì :\(\frac{2}{x}-1\frac{3}{-4}=-1\)
=>\(\frac{2}{x}+\frac{7}{4}=-1\)
=>\(\frac{2}{x}=-1-\frac{7}{4}\)
=>\(\frac{2}{x}=-\frac{11}{4}=>-11x=8\)
\(=>x=\frac{8}{-11}=\frac{-8}{11}\)