## Intermediate Algebra for College Students (7th Edition)

$(3x+4)(3x-4)$
The product of a binomial sum and a binomial difference is: $(A+B)(A-B)=A^2-B^2$. The square of a binomial sum is: $(A+B)^2=A^2+2AB+B^2$. The square of a binomial difference is: $(A-B)^2=A^2-2AB+B^2$. Hence here by deducing the area of the white squares from the big one: $A=3x\cdot 3x-4\cdot2\cdot2=(3x)^2-4^2=(3x+4)(3x-4)$