\(x^2+3x=x(x+3)\)

\(6a^2-15a=3a(2a-5)\)

\(6ab+8a=2a(3b+4)\)

\(9pq+21pr=3p(3q+7r)\)

\(10xyz+45xy=5xy(2z+9)\)

\(15x^2+24x^3=3x^2(5+8x)\)

\(5a+7a^7+a^3=a(5+7a^6+a^2)\)

\(15x^3y^4-21x^4y^5=3x^3y^4(5-7xy)\)

\(a^2-4=(a-2)(a+2)\)

\(64p^2-121=(8p-11)(8p+11)\)

\(64-25x^2=(8-5x)(8+5x)\)

\(144x^8-25=(12x^4-5)(12x^4+5)\)

\(36p^2-16=4(9p^2-4)=4(3p-2)(3p+2)\)

\(48a^3-3a=3a(16a^2-1)=3a(4a-1)(4a+1)\)

\(a^{12}-81=(a^6-9)(a^6+9)=(a^3-3)(a^3+3)(a^6+9)\)

\(3a^6-48a^2=3a^2(a^4-16)=3a^2(a^2-4)(a^2+4)=3a^2(a-2)(a+2)(a^2+4)\)

\(p^2q^{10}-r^2=(pq^5-r)(pq^5+r)\)

\(x^2+7x+6=(x+1)(x+6)\)

\(a^2+a-20=(a-4)(a+5)\)

\(p^2-10p+16=(p-8)(p-2)\)

\(x^2-18x+81=(x-9)(x-9)\)

\(a^4-3a^3-28a^2=a^2(a^2-3a-28)=a^2(a+4)(a-7)\)

\(a^8+15a^4+56=(a^4+8)(a^4+7)\)