### Instruction: Expand the following expression: $(13x+15)\cdot 2x$.### Response: To expand an expression like this, I need to use the distributive property of multiplication over addition, which says that $a\cdot(b+c)=a\cdot b+a\cdot c$.
So, I can rewrite the expression as $(13x+15)\cdot 2x=(13x)\cdot 2x+(15)\cdot 2x$.
Now, I just need to multiply each term and combine the like terms.
To multiply two terms with the same variable, I need to add their exponents.
For example, $(13x)\cdot 2x=13\cdot 2\cdot x\cdot x=26\cdot x^2$.
To multiply a constant term by a variable term, I just multiply the coefficients.
For example, $(15)\cdot 2x=15\cdot 2\cdot x=30\cdot x$.