1.

State True and False for the following (i) Integrating factor of the differential of the form (dx)/(dy)+p_(1)x=Q_(1) is given bye^(intP_(1)dy). (ii) Solution of the differential equation of the type (dx)/(dy)+P_(1)x=Q_(1) is given by x*IF=int(IF)xxQ_(1)dy. (iii) Correct substitution for the solution of the differential equation of the type (dy)/(dx)=f(x,y), where f(x, y) is homogeneous function of zero degree is y = vx. (iv) Correct substitution for the solution of the differential equation of the type (dy)/(dx)=g(x,y), where g(x,y) is a homogeneous function of the degree zero is x=vy. (v) Number of arbitrary constants in the particular solution of a differential equation of order two is two. (vi) The differential equation representing the family of circles x^(2)+(y-a)^(2)=a^(2) will be of order two. (vii) The solution of (dy)/(dx)=((y)/(x))^(1//3)"is "y^(2//3)-x^(2//3)=c (viii) Differential equation representing the family of curve y=e^(x)(Acosx+Bsinx)"is "(d^(2)y)/(dx^(2))-2(dy)/(dx)+2y=0. (ix) The solution of the differential equation (dy)/(dx)=(x+2y)/(x)"is "x+y=kx^(2). (x) Solution of (xdy)/(dx)=y+xtan""(y)/(x)"is "sin((y)/(x))=cx (xi) The differential equation of all non horizontal lines in aplane is (d^(2)x)/(dy^(2))=0.

Answer»

Solution :(i) True
Given differential equation,
`""(dx)/(dy)+P_(1)x=Q_(1)`
`therefore""IF=e^(intp_(1)dy)`
(ii) True
(iii) True
(IV) True
(v) False
There is no arbitrary constant in the particular solution of a differential equation.
(vi) False
We know that, order of the differential equation =number of arbitrary constant
Here, number of arbitrary constant = 1
So order is one.
(vii) True
Given differential equation, `""(dy)/(dx) =((y)/(x))^(1//3)`
`RARR""(dy)/(dx) =(y^(1//3))/(x^(1//3))`
`rArr""y^(-1//3)dy=x^(-1//3)dx`
On integrating both sides, we get
`""inty^(-1//3)dy=intx^(-1//3)dx`
`rArr""(y^(-1//3+1))/((-1)/(3)+1)=(x^(-1//3+1))/((-1)/(3)+1)+C'`
`rArr""(3)/(2)y^(2//3)=(3)/(2)x^(2//3)+C'`
`rArr""y^(2//3)-x^(2//3)=C'""["where",(2)/(3)C'=C]`
(viii) True
Given that, `""y=e^(x)(Acosx+Bsinx)`
On differentiating w.r.t. x, we get
`""(dy)/(dx)=e^(x)(-Asinx+Bcosx)+e^(x)(Acosx+(Bsinx)`
`rArr""(dy)/(dx)-y=e^(x)(-Asinx+Bcosx)`
Again differentiating w.r.t. x, we get
`""(d^(2)y)/(dx^(2))-(dy)/(dx)=e^(x)(-Acosx-Bsinx)+e^(x)(-Asinx-Bcosx)+e^(x)(-Asinx+Bcosx)`
`rArr""(d^(2)y)/(dx^(2))-(dy)/(dx)+y=(dy)/(dx)-y`
`rArr""(d^(2)y)/(dx^(2))-2(dy)/(dx)+2y=0`
(ix) True
Given that, `""(dy)/(dx)=(x+2y)/(x)rArr(dy)/(dx)=1+(2)/(x)*y`
`rArr""(dy)/(dx)-(2)/(x)y=1`
`""IF=e^((-2)/(x)dx)=e^(-2logx)=x^(-2)`
The differential solution,
`""y*x^(-2)=intx^(-2)*1dx+k`
`rArr""(y)/(x^(2))=(x^(-2+1))/(-2+1)+k`
`rArr""(y)/(x^(2))=(-1)/(x)+k`
`rArr""y=-x+kx^(2)`
`rArr""x+y=kx^(2)`
(x) True
Given differential equation,
`""(xdy)/(dx)=y+xtan((y)/(x))`
`rArr""(dy)/(dx)=(y)/(x)+tan((y)/(x))""`...(i) ltBrgt Put `""(y)/(x)=v" "i.e., y=vx`
`rArr""(dy)/(dx)=v+(xdv)/(dx)`
On SUBSTITUTING these values in Eq. (i), we get
`""(xdv)/(dx)+v=v+tanv`
`rArr""(dx)/(x)=(dv)/(tanv)`
On integrating both sides, we get
`""int(1)/(x)dx=int(1)/(tanv)dx`
`rArr""log(x)=log(sinv)+logC'`
`rArr""log((x)/(sinv))=logC'`
`rArr""(x)/(sinv)=C'`
`rArr""sinv=Cx""["where, C=(1)/(C')]`
`rArr""sin(y)/(x)=Cx`
(XI) True
Let any non-horizontal line in a plane is given by
`""y=mx+c`
On differentiating w.r.t. x, we get
`""(dy)/(dx)=m`
Again, differentiating w.r.t. x, we get
`""(d^(2)y)/(dx^(2))=0`


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