do vui:co a;b;c thoa man ab+bc+ac=1.cmr(a^+1)(b^+1)(c^+1) la 1 so chinh phuong
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b: Thay y=6 vào y=3x, ta được:
3x=6
hay x=2
c: Thay x=y vào y=3x, ta được:
3x=x
=>x=0
=>y=0
a: Số đo góc ở đáy là:
\(\dfrac{180^0-80^0}{2}=50^0\)
b: SỐ đo góc ở đỉnh là:
\(180^0-2\cdot80^0=20^0\)
Complete the sentences with the words in parentheses.
1.A : What ( you, do)__did you do______last Friday ?
B : I ( come )_came_____to class.
2. A :What ( you,do) _will you do_____next Friday ?
B : I ( come ) __will come___to class
3.A : What ( you,do )____did you do______yesterday evening ?
B : I ( watch)__watched_____TV.
4.A :What ( you,do )___do you do_______every evening ?
B :I ( watch)____watch___TV.
5. A :What ( you,do )___will you do_______tomorrow evening ?
B :I ( watch)___will watch____TV.
6.A : What ( you, do )____are you doing__________right now ?
B : I (do)___am doing_____ a grammar exercise.
7. A :What (Maria,do)____does marian do_____every morning ?
B : She ( go )____goes____to work
Complete the sentences with the words in parentheses.
1.A : What ( you, do)____did you do____last Friday ?
B : I ( come )____CAME__to class.
2. A :What ( you,do) ___DID YOU DO___next Friday ?
B : I ( come ) _CAME____to class
3.A : What ( you,do )______DID YOU DO____yesterday evening ?
B : I ( watch)____WATCHED___TV.
4.A :What ( you,do )____DO YOU DO______every evening ?
B :I ( watch)__WATCH_____TV.
5. A :What ( you,do )___WILL YOU DO_______tomorrow evening ?
B :I ( watch)____WILL WATCH___TV.
6.A : What ( you, do )______ARE YOU DOING________right now ?
B : I (do)_____AM DOING___ a grammar exercise.
7. A :What (Maria,do)___DOES MARIA DO______every morning ?
B : She ( go )_____GOES___to work
Thay ab+bc+ca=1 vào ta có:
(a2+ab+bc+ac)(b2+ab+ac+bc)(c2+ab+bc+ca) = [ a(a+b)+c(a+b)].[ b(a+b)+c(a+b)].[ c(a+b) +a(a+b)]
=(a+c)(a+b)(b+c)(a+b)(a+c)(b+c) = [(a+c)(a+b)(b+c)]2 là một scp.