Question 291990
Let d = distance from P to Q.

d = sqrt{(-13 + 5)^2 + (1 + 7)^2}

d = sqrt{(-8)^2 + (8)^2}

d = sqrt{64 + 64}

d = sqrt{128}

d = sqrt{16} * sqrt{8}

d = 4 * sqrt{4} * sqrt{2}

d = 4 * 2 * sqrt{2}

d = 8(sqrt{2})