x mũ 3+5x mũ2 trừ 6x giai gium nha
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5: \(=-\left(x^2+3x+5\right)\)
\(=-\left(x^2+3x+\dfrac{9}{4}+\dfrac{11}{4}\right)\)
\(=-\left(x+\dfrac{3}{2}\right)^2-\dfrac{11}{4}< 0\)
6: \(=-3\left(x^2+2x+\dfrac{4}{3}\right)=-3\left(x^2+2x+1+\dfrac{1}{3}\right)\)
\(=-3\left(x+1\right)^2-1< 0\)
a) \(\left(6x+5y\right)^2=36x^2+60x+25y^2\)
b) \(\left(4x-1\right)^2=16x^2-8x+1\)
c) \(\left(x+2\right)^2=x^2+4x+4\)
\(\left(5^2+3^2\right).x+\left(5^2-3^2\right).x=10^2\)
\(\Rightarrow x.\left(5^2+3^2+5^2-3^2\right)=10^2\)
\(\Rightarrow x.\left(25+9+25-9\right)=100\)
\(\Rightarrow x.50=100\)
\(\Rightarrow x=100:50=2\)
\(KL:......................\)
( 52 + 32 ) . x + ( h2 - 32 ) . x = 102
=> ( 25 + 9 ) . x + ( 25 - 9 ) . x = 100
=> 34 . x + 16 . x = 100
=> x ( 34 + 16) = 100
=> x . 50 = 100
=> x = \(\frac{100}{50}\)
Vậy x = 2
Bài 1:
1; 5\(x\) + \(x\) = 39 - 311 : 39
\(x\).(5 + 1) = 39 - 32
\(x.6\) = 39 - 9
\(x.6\) = 30
\(x\) = 30 : 6
\(x\) = 5
Vậy \(x\) = 5
2; 5\(x\) + \(x\) = 150 : 2 + 3
\(x\).(5 + 1) = 75 + 3
\(x.6\) = 78
\(x\) = 78 : 6
\(x\) = 13
Vậy \(x=13\)
\(x^3+5x^2-6x\)
\(=x^3+6x^2-x^2-6x\)
\(=x^2.\left(x+6\right)-x.\left(x+6\right)\)
\(=\left(x^2-x\right).\left(x+6\right)\)
\(x^3+5x^2-6x\)
\(=x\left(x^2+5x-6\right)\)
\(=x\left(x^2+6x-x-6\right)\)
\(=x\left[x\left(x+6\right)-\left(x+6\right)\right]\)
\(=x\left(x+6\right)\left(x-1\right)\)