(1/2 -1/3). 6x.6x+2=615
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a) 5y.(2y-1)-(3y+2).(3-3y)
b) (6x+1)^2 -2(6x+1).(6x-1)+(6x-1)^2
c) (2x+3)-2(2x+3)(x-2)+(x-2)^2
`a)5y(2y-1)-(3y+2)(3-3y)`
`=10y^2-5y+(3y+2)(3y-3)`
`=10y^2-5y+9y^2-9y+6y-6`
`=19y^2-8y-6`
`b)(6x+1)^2-2(6x+1)(6x-1)+(6x-1)^2`
`=(6x+1-6x+1)^2`
`=2^2=4`
`c)(2x+3)^2-2(2x+3)(x-20+(x-2)^2`
`=(2x+3-x+2)^2`
`=(x+5)^2`
`=x^2+10x+25`
\(a,=a^3+3a^2b+3ab^2+b^3-a^3+3a^2b-3ab^2+b^3-2b^3=6a^2b\\ b,=\left(6x+1-6x+1\right)^2=2^2=4\)
\(\text{a) }\left(6x+1\right)^2+\left(6x-1\right)^2-2\left(6x+1\right)\left(6x-1\right)\\ =\left[\left(6x+1\right)-\left(6x-1\right)\right]^2\\ =\left[6x+1-6x+1\right]^2\\ =2^2\\ =4\)
\(\text{b) }3\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\\ =\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\\ =\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\\ =\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\\ =\left(2^{16}-1\right)\left(2^{16}+1\right)\\ =2^{32}-1\)
\(27+\left(220-6x\right).3=615\)
\(\rightarrow\left(220-6x\right).3=615-27=588\)
\(\rightarrow220-6x=588:3=196\)
\(\rightarrow6x=220-196=24\)
\(\rightarrow x=24:6=4\)
\(315-\left(x-3\right).7=210\)
\(\Rightarrow\left(x-3\right).7=315-210=105\)
\(\Rightarrow x-3=105:7=15\)
\(\Rightarrow x=15+3=18\)
\(1,\left(x-2\right)\left(x+2\right)\left(x^2+4\right)-\left(x^2-3\right)\left(x^2+3\right)\)
\(=\left(x^2-4\right)\left(x^2+4\right)-\left(x^2-9\right)\)
\(=x^2-16-x^2+9\)
\(=-7\)
\(2,\left(6x+1\right)^2+\left(6x-1\right)^2-2\left(1+6x\right)\left(6x-1\right)\)
\(=\left(6x+1-6x+1\right)^2\)
\(=2^2=4\)
\(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\cdot6^x\cdot6^{x+2}=6^{15}\)
\(\Rightarrow\dfrac{1}{6}\cdot6^{x+2+x}=6^{15}\)
\(\Rightarrow6^{2x+3}=6^{15}:\dfrac{1}{6}\)
\(\Rightarrow6^{2x+2}=6^{16}\)
\(\Rightarrow2x+2=16\)
\(\Rightarrow2x=16-2\)
\(\Rightarrow2x=14\)
\(\Rightarrow x=7\)
1/6 . 6x . 6x.62=615
6x+2.6=615
62x = 615/6
62x =614
=>2x = 14
=>x = 14:2
=>x = 7