The matrix m = 1 & 5 2 & 7 and matrix n = 2 & 0 6 & 1 find:

Mathematics

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  1. The matrix m=(1527)m = \begin{pmatrix} 1 & 5 \\ 2 & 7 \end{pmatrix} and matrix n=(2061)n = \begin{pmatrix} 2 & 0 \\ 6 & 1 \end{pmatrix} find: a) mTm^T (already solved in previous message) b) nmnm

    b) Find nmnm.

  1. Multiply matrix nn by matrix mm.

    $$
    nm = \begin{pmatrix} 2 & 0 \\ 6 & 1 \end{pmatrix} \begin{pmatrix} 1 & 5 \\ 2 & 7 \end{pmatrix}
    $$
    
  2. Perform the matrix multiplication.

    $$
    nm = \begin{pmatrix} (2 \times 1) + (0 \times 2) & (2 \times 5) + (0 \times 7) \\ (6 \times 1) + (1 \times 2) & (6 \times 5) + (1 \times 7) \end{pmatrix}
    $$
    
  3. Calculate the values for each element.

    $$
    nm = \begin{pmatrix} 2 + 0 & 10 + 0 \\ 6 + 2 & 30 + 7 \end{pmatrix}
    $$
    $$
    nm = \begin{pmatrix} 2 & 10 \\ 8 & 37 \end{pmatrix}
    $$
    The product $nm$ is $\boxed{\begin{pmatrix} 2 & 10 \\ 8 & 37 \end{pmatrix}}$.
    

    5. yy varies directly as the square of xx and y=96y=96 when x=4x=4. Find the value of: a) the constant kk b) yy where x=5x=5 c) xx where y=24y=24

    The relationship is $y = kx^2$.
    
    **a)** Find the constant $k$.
    
  4. Substitute the given values y=96y=96 and x=4x=4 into the variation equation.

    $$
    96 = k(4^2)
    $$
    $$
    96 = 16k
    $$
    
  5. Solve for kk.

    $$
    k = \frac{96}{16}
    $$
    $$
    k = 6
    $$
    The constant $k$ is $\boxed{6}$.
    
    **b)** Find $y$ where $x=5$.
    
  6. Use the constant k=6k=6 in the variation equation y=6x2y = 6x^2.

  7. Substitute x=5x=5 into the equation.

    $$
    y = 6(5^2)
    $$
    $$
    y = 6(25)
    $$
    $$
    y = 150
    $$
    The value of $y$ is $\boxed{150}$.
    
    **c)** Find $x$ where $y=24$.
    
  8. Use the constant k=6k=6 in the variation equation y=6x2y = 6x^2.

  9. Substitute y=24y=24 into the equation.

    $$
    24 = 6x^2
    $$
    
  10. Solve for x2x^2.

    $$
    x^2 = \frac{24}{6}
    $$
    $$
    x^2 = 4
    $$
    
  11. Take the square root of both sides.

    $$
    x = \pm\sqrt{4}
    $$
    $$
    x = \pm 2
    $$
    The values of $x$ are $\boxed{2 \text{ or } -2}$.
    

    6. Solve the equation 2x2=52x^2 = 5

  12. Isolate x2x^2 by dividing both sides by 2.

    $$
    x^2 = \frac{5}{2}
    $$
    
  13. Take the square root of both sides.

    $$
    x = \pm\sqrt{\frac{5}{2}}
    $$
    
  14. Rationalize the denominator by multiplying the numerator and denominator by 2\sqrt{2}.

    $$
    x = \pm\frac{\sqrt{5}}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}}
    $$
    $$
    x = \pm\frac{\sqrt{10}}{2}
    $$
    The solutions for $x$ are $\boxed{\pm\frac{\sqrt{10}}{2}}$.
    

    7. PP varies inversely as the square of nn and directly as mm. And P=6P=6 when n=2n=2 and m=27m=27. Find the value of: a) The constant kk b) PP when n=−6n=-6 and m=−2m=-2 c) nn when m=8m=8 and P=1P=1

    The relationship is $P = k \frac{m}{n^2}$.
    
    **a)** Find the constant $k$.
    
  15. Substitute the given values P=6P=6, n=2n=2, and m=27m=27 into the variation equation.

    $$
    6 = k \frac{27}{2^2}
    $$
    $$
    6 = k \frac{27}{4}
    $$
    
  16. Solve for kk.

    $$
    k = \frac{6 \times 4}{27}
    $$
    $$
    k = \frac{24}{27}
    $$
    
  17. Simplify the fraction.

    $$
    k = \frac{8}{9}
    $$
    The constant $k$ is $\boxed{\frac{8}{9}}$.
    
    **b)** Find $P$ when $n=-6$ and $m=-2$.
    
  18. Use the constant k=89k=\frac{8}{9} in the variation equation P=89mn2P = \frac{8}{9} \frac{m}{n^2}.

  19. Substitute n=−6n=-6 and m=−2m=-2 into the equation.

    $$
    P = \frac{8}{9} \frac{-2}{(-6)^2}
    $$
    $$
    P = \frac{8}{9} \frac{-2}{36}
    $$
    
  20. Simplify the expression.

    $$
    P = \frac{8}{9} \times \left(-\frac{1}{18}\right)
    $$
    $$
    P = -\frac{8}{162}
    $$
    $$
    P = -\frac{4}{81}
    $$
    The value of $P$ is $\boxed{-\frac{4}{81}}$.
    
    **c)** Find $n$ when $m=8$ and $P=1$.
    
  21. Use the constant k=89k=\frac{8}{9} in the variation equation P=89mn2P = \frac{8}{9} \frac{m}{n^2}.

  22. Substitute m=8m=8 and P=1P=1 into the equation.

    $$
    1 = \frac{8}{9} \frac{8}{n^2}
    $$
    $$
    1 = \frac{64}{9n^2}
    $$
    
  23. Solve for n2n^2.

    $$
    9n^2 = 64
    $$
    $$
    n^2 = \frac{64}{9}
    $$
    
  24. Take the square root of both sides.

    $$
    n = \pm\sqrt{\frac{64}{9}}
    $$
    $$
    n = \pm\frac{8}{3}
    $$
    The values of $n$ are $\boxed{\frac{8}{3} \text{ or } -\frac{8}{3}}$.
    

    8. The sketch shows the graph of y=x2−2x−8y = x^2 - 2x - 8. Find the coordinates of: a) A and B b) the minimum point on the graph

    **a)** Find the coordinates of A and B.
    
  25. A and B are the x-intercepts, where y=0y=0.

    Set the equation to 0. x2−2x−8=0 x^2 - 2x - 8 = 0

  26. Factor the quadratic equation.

    $$
    (x-4)(x+2) = 0
    $$
    
  27. Solve for xx.

    $$
    x-4=0 \Rightarrow x=4
    $$
    $$
    x+2=0 \Rightarrow x=-2
    $$
    
  28. Assign the coordinates based on the sketch (A is negative, B is positive).

    The coordinates of A are $\boxed{(-2, 0)}$ and B are $\boxed{(4, 0)}$.
    
    **b)** Find the minimum point on the graph.
    
  29. The x-coordinate of the minimum point (vertex) of a parabola y=ax2+bx+cy = ax^2 + bx + c is given by x=−b2ax = -\frac{b}{2a}.

    For y=x2−2x−8y = x^2 - 2x - 8, a=1a=1 and b=−2b=-2. x=−−22(1) x = -\frac{-2}{2(1)} x=22 x = \frac{2}{2} x=1 x = 1

  30. Substitute the x-coordinate back into the equation to find the y-coordinate.

    $$
    y = (1)^2 - 2(1) - 8
    $$
    $$
    y = 1 - 2 - 8
    $$
    $$
    y = -9
    $$
    The minimum point on the graph is $\boxed{(1, -9)}$.
    
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