Here is a trick that not a lot of people know
(# of terms)*(first+last)/2
(in case you don't know, * means multiply and / means divide)
6x15= 90
9x20= 180
180+90= 270
270 - 25 = 245 dane has 245 stamps left
Let's solve your equation step-by-step.<span><span><span>−18</span>−<span>6k</span></span>=<span>6<span>(<span>1+<span>3k</span></span>)
</span></span></span>Step 1: Simplify both sides of the equation.
<span><span><span>−18</span>−<span>6k</span></span>=<span>6<span>(<span>1+<span>3k</span></span>)
</span></span></span><span>Simplify: (Show steps)</span><span><span><span>−<span>6k</span></span>−18</span>=<span><span>18k</span>+6
</span></span>Step 2: Subtract 18k from both sides.<span><span><span><span>−<span>6k</span></span>−18</span>−<span>18k</span></span>=<span><span><span>18k</span>+6</span>−<span>18k</span></span></span><span><span><span>−<span>24k</span></span>−18</span>=6
</span>Step 3: Add 18 to both sides.<span><span><span><span>−<span>24k</span></span>−18</span>+18</span>=<span>6+18</span></span><span><span>−<span>24k</span></span>=24
</span>Step 4: Divide both sides by -24.<span><span><span>−<span>24k</span></span><span>−24</span></span>=<span>24<span>−24</span></span></span><span>k=<span>−1
</span></span>Answer:<span>k=<span>−<span>1</span></span></span>
This is the concept of application of the Pythagorean theorem. The resultant speed of the motorboat which is crossing the river that has a northward current of 5 m/s at a speed of 8 m/s will be given by:
c^2=a^2+b^2
c^2=8^2+5^2
c^2=64+25
c^2=89
c=sqrt89
c=9.4 m/s
