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\(M=\left(2x+3\right)\left(2a-3\right)\left(4a^2+9\right)-\left(a^2+5\right)\left(a^2-5\right)\)
\(=\left(4a^2-9\right)\left(4a^2+9\right)-a^2+25\)
\(=16a^4-81-a^2+25\)
\(=16a^4-a^2-56\)
M = ( 2a+3)(2x-3)(4a2+9) - (a2 + 5)(a2 - 5)
M =[ (2a)2 - 32 ][(2a2)+ 32 ] - [(a2)2 - 52 ]
M = (4a2)2 - (32)2 - a4 + 25
M = 16a4 - 81 - a4 +25
M = 15a4 - 56
2.
\(P=\left(\dfrac{a+6}{3\left(a+3\right)}-\dfrac{1}{a+3}\right).\dfrac{27a}{a+2}=\left(\dfrac{a+3}{3\left(a+3\right)}\right).\dfrac{27a}{a+2}=\dfrac{27a}{3\left(a+2\right)}=\dfrac{9a}{a+2}\)
ĐKXĐ là :
\(a\ne0;-3;-2\)
Vs a = 1 ta có:
=> P=3
1.
\(M=\left(\dfrac{2a}{2a+b}-\dfrac{4a^2}{\left(2a+b\right)^2}\right):\left(\dfrac{2a}{\left(2a-b\right)\left(2a+b\right)}-\dfrac{1}{2a-b}\right)=\left(\dfrac{4a^2+2ab-4a^2}{\left(2a+b\right)^2}\right).\left(\dfrac{\left(2a+b\right)\left(2a-b\right)}{b}\right)=\dfrac{2a.\left(2a-b\right)}{\left(2a+b\right)}\)
a. Ta có: a > b
4a > 4b ( nhân cả 2 vế cho 4)
4a - 3 > 4b - 3 (cộng cả 2 vế cho -3)
b. Ta có: a > b
-2a < -2b ( nhân cả 2 vế cho -2)
1 - 2a < 1 - 2b (cộng cả 2 vế cho 1)
d. Ta có: a < b
-2a > -2b ( nhân cả 2 vế cho -2)
5 - 2a > 5 - 2b (cộng cả 2 vế cho 5)
b)\(2a^2-3+5a\)
\(=\left(2a^2+6a\right)-\left(a+3\right)\)
\(=\left(a+3\right)\left(2a-1\right)\)
d)\(2a^2-5-3a\)
\(=\left(2a^2+2a\right)-\left(5a+5\right)\)
\(=\left(a+1\right)\left(2a-5\right)\)
a) \(a^2-3-2a\)
\(=a^2-2a+1-4\)
\(=\left(a^2-2a+1\right)-2^2\)
\(=\left(a-1\right)^2-2^2\)
\(=\left(a-1-2\right)\left(a-1+2\right)\)
\(=\left(a-3\right)\left(a+1\right)\)
c) \(4a+a^2+3\)
\(=a^2+4a+4-1\)
\(=\left(a^2+4a+4\right)-1^2\)
\(=\left(a+2\right)^2-1^2\)
\(=\left(a+2-1\right)\left(a+2+1\right)\)
\(=\left(a+1\right)\left(a+3\right)\)
\(\left(2a+3\right)\left(2a-3\right)\left(4a^2+9\right)-\left(a^2+5\right)\left(a^2-5\right)\)
\(=16a^4-81-\left(a^2+5\right)\left(a^2-5\right)\)
\(=16a^4-81-a^4+25\)
\(=15a^4-56\)
Bn ko ghi yk nên mk làm thế này thôi nhé :))
\(\left(2a+3\right)\left(2a-3\right)\left(4a^2+9\right)-\left(a^2+5\right)\left(a^2-5\right)\)
\(=\left(4a^2-9\right)\left(4a^2+9\right)-\left(a^4-25\right)\)
\(=16a^4-81-a^4+25\)
\(=15a^4-56\)