Suppose that a and b are any n-vectors. Show that we can always find a scalar γ so that (a − γb) ⊥ b, and that γ is unique if $b \neq 0$ . Recall that given two vectors a,b a⊥ b if and only if $a\cdot b =0$ where $\cdot$ is the dot product defined in $\mathbb{R}^n$ . Suposse that $b\neq 0$ . We want to find γ such that $(a-\gamma b)\cdot b=0$ . Given that the dot product can be distributed and that it is linear, the following equation is obtained

$(a-\gamma b)\cdot b = 0 = a\cdot b - (\gamma b)\cdot b= a\cdot b - \gamma b\cdot b$

Recall that $a\cdot b, b\cdot b$ are both real numbers, so by solving the value of γ, we get that

$\gamma= \frac{a\cdot b}{b\cdot b}$

By construction, this γ is unique if $b\neq 0$ , since if there was a $\gamma_2$ such that $(a-\gamma_2b)\cdot b = 0$ , then

$\gamma_2 = \frac{a\cdot b}{b\cdot b}= \gamma$

6 0

3 years ago

Using the quadratic formula to solve 5x = 6x2 – 3, what are the values of x?

elena55 [62]

6x2 -5x –3 = 0
a = 6 b=-5 and c=-3

x = [-b +-sq root (b² -4ac)] / 2a
x = [--5 +-sq root (25 -4*6*-3)] / 2*6
x = [5 +- sq root (25 +72)] / 12
x = [5 +- sq root (97)] / 12

x1 = [5 + 9.8488578018 ] / 12
x1 = 14.8488578018 / 12
x1 = 1.2374048168 

x2 = [5 - 9.8488578018 ] / 12
x2 = -4.8488578018 / 12
x2 = -0.4040714835

5 0

4 years ago