tim y bang 2 cach:
(52+y)-32=64
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a) 365.12.4+365.52=365.(12.4)+365.52=365.48+365.52=365.(48+52)=365.100=36 500
b)48.18+24.64=24.2.18+24.64=24.(2.18)+24.64=24.36+24.64=24.(36+64)=24.100=2 400
a)365x12x4+365x2
=365x48+365x2
=365(48+20
=365x50
=18250
b)48x18+24x64
=48x18+24x2x32
=48x18+48x32
=48x(18+32)
=48x50
=2400
(P): y= -1/2x2
(d): y= x-3/2
(d'): y= mx+1/2
-1/2x2 = x-3/2
=> -1/2x2 - x + 3/2 = 0
=> x = 1 ; x = 3
Thay x = 1 ; x = 3 vao (P)
=>y = -1/2 .12 = -1/2 ; y = -1/2 .(-3) 2 = -9/2
Vay giao diem cua (P) & (d) la (1 ; -1/2 ) (3 ; -9/2)
b.xet PTHDGD cua (P) & (d’)
mx+1/2 = -1/2x2
1/2x2 - mx -1/2 = 0
Δ = b2 - 4ac = (-m) 2 - 4.\(\frac{1}{2}\)\(\frac{1}{2}\) =m 2 - 1
De (P) txuc vs (d’) <=> Δ = 0 <=> m 2 - 1 = 0
<=>m = ± \(\sqrt{ }\)1
hinh nhu dung r day
A=\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{256}\)
A=\(\left(1-\frac{1}{2}\right)+\left(\frac{1}{2}-\frac{1}{4}\right)+\left(\frac{1}{4}-\frac{1}{8}\right)+...+\left(\frac{1}{128}-\frac{1}{256}\right)\)
A=\(1-\frac{1}{256}\)
A=\(\frac{255}{256}\)
A = 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256
2A = 1/2 x 2 + 1/4 x 2 + 1/8 x 2 + 1/16 x 2 +1/32 x 2 + 1/64 x 1/128 + 1/256 x 2
2A = 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128
2A - A = ( 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 ) - ( 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 )
A = 1 - 1/256
A = 255/256
Ta có
a, x2-x-y2-y
=x2-y2-(x+y)
=(x-y)(x+y) - (x+y)
=(x+y)(x-y-1)
b, x2-2xy+y2-z2
=(x-y)2-z2
=(x-y-z)(x-y+z)
2. =5(x2-2.1/10.x+1/100-y2+2.1/10y-1/100)
=5.((X-1/10)2-(Y-1/10)2)
=5(X-1/10-Y+1/10)(X-1/10+Y-1/10)
=5(X-Y)(X+Y-2/10)
cach 1:
(52+y)-32=64
52+y =64+32
52+y =96
y =96-52
y =44
cach 2:
(52+y)-32=64
52-32+y=64
20+y=64
y=64-20
y=44
c1:
(52+y)-32=64
52+y=64+32
52+y=96
y=96-52
y=44
c2:
(52+y)-32=64
y-32=64-52
y=12+32
y=44