a) 4.25-12.5+170:10

=100-60+17

=40+17

=57

b) (7+3³:3²).4-3

=(7+3).4-3

=10.4-3

=40-3

=37

c) 12:{400:[500-(125+25.7)]}

=12:{400:[500-(125+175)]}

=12:{400:[500-300]}

=12:{400:200}

=12:2

=6

d) 168+{[2.(2⁴+3²)-256⁰]:7²}

=168+{[2.(16+9)-1]:49}

=168+{[2.25-1]:49}

=168+{[50-1]:49}

=168+{49:49}

=168+1

=169

\(2^x+5\cdot2^{x+2}=168\)

=>\(2^x+20\cdot2^x=168\)

=>\(21\cdot2^x=168\)

=>\(2^x=8=2^3\)

=>x=3

\(2^x+5.2^{x+2}=168\\ \Leftrightarrow2^x.\left(1+5.2^2\right)=168\\ \Leftrightarrow2^x.21=168\\ \Leftrightarrow2^x=\dfrac{168}{21}=8=2^3\\ Vây:x=3\)

2x+5.2x+2=168⇔2x.(1+5.22)=168⇔2x.21=168⇔2x=16821=8=23

Vây:x=3

a) \(\dfrac{10^{12}+5^{11}.2^9-5^{13}.2^8}{4.5^5.10^6}\)

\(=\dfrac{2^{12}.5^{12}+5^{11}.2^9-5^{13}.2^8}{2^2.5^5.2^6.5^6}\)

\(=\dfrac{2^{12}.5^{12}+5^{11}.2^9-5^{13}.2^8}{2^8.5^{11}}\)

\(=\dfrac{\left(2^8.5^{11}\right)\left(2^4.5+2-5^2\right)}{2^8.5^{11}}\)

\(=2^4.5+2-5^2\)

\(=57\)

b) \(\dfrac{\left[5\left(x-y\right)^4-3\left(x-y\right)^3+4\left(x-y\right)^2\right]}{\left(y-x\right)^2}\)

\(=\dfrac{\left(x-y\right)^2\left[5\left(x-y\right)^2-3\left(x-y\right)+4\right]}{\left(y-x\right)^2}\)

\(=\dfrac{\left(x^2+y^2-2xy\right)\left[5\left(x-y\right)^2-3\left(x-y\right)+4\right]}{\left(y^2+x^2-2xy\right)}\)

\(=5\left(x-y\right)^2-3\left(x-y\right)+4\)

c) \(\dfrac{\left(x+y\right)^5-2\left(x+y\right)^4+3\left(x+y\right)^3}{-5\left(x+y\right)^3}\)

\(=\dfrac{\left(x+y\right)^3\left[5\left(x+y\right)^2-2\left(x+y\right)+3\right]}{-5\left(x+y\right)^3}\)

\(=\dfrac{5\left(x+y\right)^2-2\left(x+y\right)+3}{-5}\)

Nhóm 1: 5x^2y^3;x^2y^3;1/2x^2y^3;x^2y^3

Tổng là 6,5x^2y^3

Nhóm 2: 10x^3y^2;-3x^3y^2;-5x^3y^2

Tổng là 2x^3y^2

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