Answer:
n = 3
Step-by-step explanation:
Isosceles means that the left and right sides (non-parallel sides) are equal to each other and so the base angles are also equal to each other. Then you can make an equation with the 8n^2-11 set equal to the 2n^2+7.
see image.
To solve it you have to set everything equal to zero (get all terms on one side of the equation) FACTOR (you end up with the difference of two squares) and solve, using zero product property. See image.
