You're on a roll — here are the solutions to the problems from the image.
: If 3x2−5y3+xy−1=0, find dxdy at the point (5,−2).
Step 1: Differentiate the given equation implicitly with respect to x.
dxd(3x2)−dxd(5y3)+dxd(xy)−dxd(1)=dxd(0)
Applying the power rule, chain rule, and product rule:
6x−15y2dxdy+(1⋅y+x⋅dxdy)−0=0
6x−15y2dxdy+y+xdxdy=0
Step 2: Group terms containing dxdy and terms not containing dxdy.
(x−15y2)dxdy=−6x−y
Step 3: Solve for dxdy.
dxdy=x−15y2−6x−y
Step 4: Substitute the given point (x,y)=(5,−2) into the expression for dxdy.
dxdy=5−15(−2)2−6(5)−(−2)
dxdy=5−15(4)−30+2
dxdy=5−60−28
dxdy=−55−28
dxdy=5528
The value of dxdy at the point (5,−2) is:
\frac{28{55}}
: Given that A=(x2133x) and B=(326x), find the possible values of x such that AB=BA.
Step 1: Calculate the product AB.
AB=(x2133x)(326x)
AB=((x2)(3)+(3)(2)(1)(3)+(3x)(2)(x2)(6)+(3)(x)(1)(6)+(3x)(x))
AB=(3x2+63+6x6x2+3x6+3x2)
Step 2: Calculate the product BA.
BA=(326x)(x2133x)
BA=((3)(x2)+(6)(1)(2)(x2)+(x)(1)(3)(3)+(6)(3x)(2)(3)+(x)(3x))
BA=(3x2+62x2+x9+18x6+3x2)
Step 3: Set AB=BA and equate the corresponding elements.
(3x2+63+6x6x2+3x6+3x2)=(3x2+62x2+x9+18x6+3x2)
Equating the top-left elements: 3x2+6=3x2+6 (This is always true).
Equating the bottom-right elements: 6+3x2=6+3x2 (This is always true).
Equating the top-right elements:
6x2+3x=9+18x
6x2+3x−18x−9=0
6x2−15x−9=0
Divide by 3:
2x2−5x−3=0
Equating the bottom-left elements:
3+6x=2x2+x
0=2x2+x−6x−3
0=2x2−5x−3
Both equations yield the same quadratic equation.
Step 4: Solve the quadratic equation 2x2−5x−3=0.
We can factor the quadratic equation:
2x2−6x+x−3=0
2x(x−3)+1(x−3)=0
(2x+1)(x−3)=0
Set each factor to zero to find the values of x:
2x+1=0⟹2x=−1⟹x=−21
x−3=0⟹x=3
The possible values of x are:
x = -\frac{1{2} or x = 3}
What's next?