- E

G = 5 + √7 (9 – R)² + 9

G – 5 = √7 (9 – R)² + 9

Squaring both sides,

(G – 5)² = 7 (9 – R)² + 9

(G – 5)² – 9 = 7 (9 – R)²

(G – 5)² – 9 = (9 – R)²

7

Square Rooting on both sides,

√(G – 5)² – 9 = 9 – R

7

{√(G – 5)² – 9} – 9 = – R

7

To change the sign of R from negative to positive, we need to multiply both sides by -1

(-1) x {√(G – 5)² – 9} – 9 = – R (-1)

7

R = 9 – {√(G – 5)² – 9}

7

i saw thats the way to solve it but i cant understand why its cant be D