ai làm bài này với
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Những câu hỏi liên quan
20 tháng 8 2021
1: Ta có: \(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+9\left(x+1\right)^2=15\)
\(\Leftrightarrow x^3-3x^2+27x-27-x^3+27+9x^2+18x+9=15\)
\(\Leftrightarrow45x=6\)
hay \(x=\dfrac{2}{15}\)
2: Ta có: \(x\left(x-5\right)\left(x+5\right)-\left(x+2\right)\left(x^2-2x+4\right)=3\)
\(\Leftrightarrow x^3-25x-x^3-8=3\)
\(\Leftrightarrow-25x=11\)
hay \(x=-\dfrac{11}{25}\)
3: Ta có: \(\left(x+4\right)\left(x^2-4x+16\right)-x\left(x-5\right)\left(x+5\right)=264\)
\(\Leftrightarrow x^3+64-x^3+25x=264\)
\(\Leftrightarrow25x=200\)
hay x=8
4: Ta có: \(\left(x-2\right)^3-\left(x-2\right)\left(x^2+2x+4\right)+6\left(x-2\right)\left(x+2\right)=60\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3+8+6x^2-24=60\)
\(\Leftrightarrow12x=84\)
hay x=7
20 tháng 8 2021
6: Ta có: \(\left(x+2\right)^3-\left(x-2\right)^3=64\)
\(\Leftrightarrow x^3+6x^2+12x+8-x^3+6x^2-12x+8=64\)
\(\Leftrightarrow12x^2=48\)
\(\Leftrightarrow x^2=4\)
hay \(x\in\left\{2;-2\right\}\)
7: Ta có: \(\left(5x-1\right)^2-\left(5x-4\right)\left(5x+4\right)=7\)
\(\Leftrightarrow25x^2-10x+1-25x^2+16=7\)
\(\Leftrightarrow-10x=-10\)
hay x=1
8: Ta có: \(\left(4x+1\right)^2-\left(2x+3\right)^2+5\left(x+2\right)^2+3\left(x-2\right)\left(x+2\right)=500\)
\(\Leftrightarrow16x^2+8x+1-4x^2-12x-9+5x^2+20x+20+3x^2-12=500\)
\(\Leftrightarrow20x^2+16x-500=0\)
\(\text{Δ}=16^2-4\cdot20\cdot\left(-500\right)=40256\)
Vì Δ>0 nên phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{-16-8\sqrt{629}}{40}=\dfrac{-2-\sqrt{629}}{5}\\x_2=\dfrac{-16+8\sqrt{629}}{40}=\dfrac{-2+\sqrt{629}}{5}\end{matrix}\right.\)
9: Ta có: \(\left(x-3\right)\left(x^2+3x+9\right)+x\left(x+2\right)\left(2-x\right)=1\)
\(\Leftrightarrow x^3-27-x^3+4x=1\)
\(\Leftrightarrow4x=28\)
hay x=7
17 tháng 8 2021
Bài 3:
1: \(35^2=1225\)
2: \(25^2=625\)
3: \(75^2=5625\)
4: \(95^2=9025\)
5: \(101\cdot99=9999\)
6: \(36\cdot44=1584\)
7: \(72\cdot68=4896\)
26 tháng 1 2022
1. goes - go
2. plays
3. studies
4. flies
5. designs
6. eat
7. works
8. grows
9. sings
10. do
11. cook - cooks
12. carries - carry
23 tháng 1 2022
a, 4,78+x=5,6 <=> x=5,6-4,78 = 0,82
b, x-3,92=0,61 <=> x = 3,92 + 0,61 = 4,53
c, 7-x=4,52 <=> x = 7-4,52 = 2,48
23 tháng 1 2022
a: =>x=5,6-4,78=0,82
b: =>x=0,61+3,92=4,53
c: =>x=7-4,52=2,48
d: =>x=17,1:4,5=3,8
e: =>x=17,1x4,5=76,95
f: =>x=42,16:6,2=6,8
ai làm giúp mình bài này với
NV
4
10 tháng 2 2022
1. B
2. D
3. A
4. B
5. C
-Vì có quá nhiều câu hỏi nên mình chỉ giúp bạn đến đây, bạn tự làm nhé.
17 tháng 8 2021
1: \(x^2-2x+1=\left(x-1\right)^2\)
2: \(4x^2-4x+1=\left(2x-1\right)^2\)
3: \(16x^2+8x+1=\left(4x+1\right)^2\)
4: \(9x^2+12x+4=\left(3x+2\right)^2\)
5: \(x^2-x+\dfrac{1}{4}=\left(x-\dfrac{1}{2}\right)^2\)
A
1. wear -> wears
2. help -> helps
3. miss -> misses
4. drink -> drinks
5. study -> studies
6. live -> lives
7. carry -> carries
8. talk -> talks
9. try -> tries
10. do -> does
11. spell -> spells
12. run -> runs
13. mix -> mixes
14. work -> works
15. wash -> washes
16. walk -> walks
17. clean -> cleans
18. fry -> fries
19. sit -> sits
20. finish -> finishes
21. call -> calls
22. play -> plays
23. listen -> listens
24. sleep -> sleeps
B.
1. goes - go
2. plays
3. studies
4. flies
5. designs
6. eat
7. works
8. grows
9. sings
10. do
11. cook - cooks
12. carries - carry
wear:wears
try: tries
clean:cleans
help:helps
do:does
fry:fries
miss:misses
spell:spells
sit:sits
drink:drinks
run:runs
finsh:finshes
study:studies
mix:mixes
call:calls
live:lives
work:works
play:plaies
carry:carries
wash:washes
listen:listens
talk:talks
walk:walks
sleep:sleeps