Expand $(a - 2b + 7c)^2$.

Evaluate the following using suitable identities:
$(107)^{2}$

Which of the following is one of the zeros of the polynomial $x^{3}-3x^{2}-5x+15$?

Which of the following expressions are polynomials in one variable and which are not? State reason for your answer. If the given expression is a polynomial,state whether it is a polynomial in one variable or not: $x^{2}-8x+15$

Prove that $(a+b+c)^{3}-a^{3}-b^{3}-c^{3}=3(a+b)(b+c)(c+a).$

Find the value of $x^{3}+y^{3}-12xy+64$,when $x+y=-4$.