the answers are B,D and F
Let <em>a</em> and <em>b</em> be the two numbers. Then
<em>a</em> + <em>b</em> = -4
<em>a b</em> = -2
Solve the second equation for <em>b</em> :
<em>b</em> = -2/<em>a</em>
Substitute this into the first equation:
<em>a</em> - 2/<em>a</em> = -4
Multiply both sides by <em>a</em> :
<em>a</em>² - 2 = -4<em>a</em>
Move 4<em>a</em> to the left side:
<em>a</em>² + 4<em>a</em> - 2 = 0
Use the quadratic formula to solve for <em>a</em> :
<em>a</em> = (-4 ± √(4² - 4(-2))) / 2
<em>a</em> = -2 ± √6
If <em>a</em> = -2 + √6, then
-2 + √6 + <em>b</em> = -4
<em>b</em> = -2 - √6
In the other case, we end up with the same numbers, but <em>a</em> and <em>b</em> are swapped.
If the triangle is a right triangle, then
(3x)² + x² = (10)² .
9x² + x² = 100
10x² = 100
x² = 10
x = √10 = approx. 3.1622...
If ' x ' is <em>anything less than √10</em> , then the short sides are too short
to make a right angle at the top, and the angle where they meet
is obtuse.
' x ' has to be greater than 2.5 ... otherwise the two short sides
can't stretch far enough to reach both ends of the long side (10) .
So, if 2.5 < x < √10 , then there is a triangle, and it's obtuse.
<span>10+(23+10×9)+50÷10</span>
<span><span><span>10+23+90+50÷10
</span></span></span><span><span><span>10+23+90+5
</span></span></span><span>128</span>
