Answer:
A
Step-by-step explanation:
Given the 2 equations
4x + 5y = - 12 → (1)
- 2x + 3y = - 16 → (2)
Eliminate the x- term by multiplying (2) by 2 and adding the result to (1)
- 4x + 6y = - 32 → (3)
Add (1) and (3) term by term
11y = - 44 ( divide both sides by 11 )
y = - 4
|DF| = |DE| + |EF| |DF| = 9x -36 |DE| = 47 |EF| = 3x+10 Substitute: 9x - 39 = 47 + 3x + 10 9x - 39 = 3x + 57 |+39 9x = 3x + 96 |-3x 6x = 96 |:6 x = 16 Put the value of x to the equation |EF| = 3x + 10 |EF| = (3)(16) + 10 = 48 + 10 = 58 Answer: |EF| = 58
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Answer:
x = - 5, x = 4
Step-by-step explanation:
Given
f(x) = x² + x - 20
To find the zeros equate f(x) to zero, that is
x² + x - 20 = 0
Consider the factors of the constant term ( - 20) which sum to give the coefficient of the x- term ( + 1)
The factors are + 5 and - 4, since
5 × - 4 = - 20 and + 5 - 4 = + 1, hence
(x + 5)x - 4) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 5 = 0 ⇒ x = - 5
x - 4 = 0 ⇒ x = 4
Answer:
Only d) is false.
Step-by-step explanation:
Let
be the characteristic polynomial of B.
a) We use the rank-nullity theorem. First, note that 0 is an eigenvalue of algebraic multiplicity 1. The null space of B is equal to the eigenspace generated by 0. The dimension of this space is the geometric multiplicity of 0, which can't exceed the algebraic multiplicity. Then Nul(B)≤1. It can't happen that Nul(B)=0, because eigenspaces have positive dimension, therfore Nul(B)=1 and by the rank-nullity theorem, rank(B)=7-nul(B)=6 (B has size 7, see part e)
b) Remember that
. 0 is a root of p, so we have that
.
c) The matrix T must be a nxn matrix so that the product BTB is well defined. Therefore det(T) is defined and by part c) we have that det(BTB)=det(B)det(T)det(B)=0.
d) det(B)=0 by part c) so B is not invertible.
e) The degree of the characteristic polynomial p is equal to the size of the matrix B. Summing the multiplicities of each root, p has degree 7, therefore the size of B is n=7.
Use an addition or subtraction formula to find the exact value of the expression, as demonstrated in example 1. tan(105°)