Answer:
2x-5= -20
move -5 to the other side
sign changes from -5 to 5
2x-5+5= -20+5
2x= -15
divide by 2 for both sides
2x/2= -15/2
cross out 2 and 2, divide by 2 and 2 and then becomes x
x= -15/2
Square root of 8 = 2.82842712475
Square root of 50 = <span>7.07106781187
</span>
Sum = 9.89949494
If you would like to round, you can go ahead and round 9.89949494 to 9.9
Sin (A + B) = sin A cos B + cos A Sin B
<span>Cos (A - B) = cos A cos B + sin A sin B </span>
<span>=> (SinACosB+ CosASinB) (CosACosB +SinASinB) </span>
<span>=>SinACosACos^2B+Sin^2ACosBSinB+Cos^2A... </span>
<span>=>SinACosA(Cos^2B+Sin^2B) +SinBCosB(Sin^2A+Cos^2A) </span>
<span>we know that Sin^2+Cos^2=1 </span>
<span>=>SinACosA(1)+SinBCosB(1) </span>
<span>=SinACosA+SinBCosB </span>
<span>Proved
</span>
All of them can be divided by 2 so ratio 1:2 is a common ratio
