Calculate the value

$21.$ $3+1\dfrac {1} {5}+\dfrac {2} {3}$ $15$ 

In the following problem $a,b,$ b,and c represent REAL NUMBERS. 
The derivative of $g\left(x\right)=log _{a}\left(bx\right)+cx^{2}is$ 
$○$ $g^{1}\left(x\right)=\right)dfrac\left(b\right)log _{-}a\left(bx\right)\right)\left(N1n$ $a\right)+2cx1\right)$ 
$○$ $\left(g\left(x\right)=\right)dtracb$ $loga\left(bx\right)+2c\times \right)Nln$ a}\) 
$○$ $g^{'}\left(x\right)=\left(dfraC\left(a\right)log _{-}a\left(bx\right)\right)\left(ln$ $\right)+2c\times 1\right)\right)$ 
$○$ $g^{1}\left(x\right)=\left(dfrac\left(b$ $log _{-}a\left(bx\right)\right)\left(ln$ $a1\right)$ 
$○$ $\left(\left(g^{1}\left(x\right)=b$ $log _{-}a\left(bx\right)+2cx1\right)$ 
$○$ $g\left(x\right)=\left(dfrac\left(b$ $log _{-}a\left(bx\right)\right)\left(1ln$ $a|+2c1\right)$ 

Question $14$ Not yet answered 
Marked out of $1.00$ 
$1+x$ $x=\sqrt{\left(Nfrac\left(2ab\right)\left(a} +b\right)$ $1\right)$ then the value of $\right)$ 
$\left(fr0c\left(x+a\right)\left(x-a\right)+lfrac\left(x+b\right)\left(x-b\right)$ $1\right)$ $1s$ Select $One$ 
a. $a/b$ 
b. $1$ $○$ 
$c2$ $2$ $○$ 
d. $a^{2}+b^{2}$ $○$ 
CLEAR MY CHOICE 

$38$ $1\dfrac {1} {2}:2\dfrac {2} {3}$ 
$15$ 
$1\dfrac {2} {3}:2\dfrac {1} {2}$ 

$\left(3\right)$ $\left(1\right)$ $27$ $\left(2\right)$ $b$ 
$48$ 
$\left(+\right)$ $6A$ 

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