Answer:
The answer is D. 
Step-by-step explanation:

simplify the expression by multiplying

calculate the product

express with a positive exponent using 
Answer:
i think i used it before
Step-by-step explanation:
Translate to english and i can help
Consider the contrapositive of the statement you want to prove.
The contrapositive of the logical statement
<em>p</em> ⇒ <em>q</em>
is
¬<em>q</em> ⇒ ¬<em>p</em>
In this case, the contrapositive claims that
"If there are no scalars <em>α</em> and <em>β</em> such that <em>c</em> = <em>α</em><em>a</em> + <em>β</em><em>b</em>, then <em>a₁b₂</em> - <em>a₂b₁</em> = 0."
The first equation is captured by a system of linear equations,

or in matrix form,

If this system has no solution, then the coefficient matrix on the right side must be singular and its determinant would be

and this is what we wanted to prove. QED
Answer:
The equation should be h²=P²+b²
27²=15²+18²
729=225+324
729=549
thus, it is not right angle triangle