Simplify the expression:$2a-2b-10+4a+b$
$=(2a+4a)+(-2b+b)-10=6a-b-10$

Substituting  $a=5$ and $b=1$ in the above expression,

$6a-b-10$ 
$=(6\times 5)-1-10$
$=30-11$
$=19$

A trinomial is defined as a polynomial which contains three unlike terms. The expression $5a{b}^3+22abc+10bc$ has three unlike terms and hence, it is a trinomial. 

An algebraic expression is a mathematical phrase that contains numbers, variables (represented by lower case letters of the English alphabet) and operators (such as addition, subtraction, multiplication  and division). 
Here are some examples of algebraic expressions: 
$a+1,$ $a–b,$  $3x,$ $\frac{4}{3},$ etc.
Hence, $2+3x$ is an algebraic expression.

$Given,2x^2+6a–5x+10=25$
Substituting the value of x = 1 in the above equation, we get,

$2(1{)}^2+6a-5(1)+10=25$

$\Rightarrow$ 2 + 6a - 5 + 10 = 25
$\Rightarrow$ 6a  + 7 = 25 

$\Rightarrow$ 6a = 25 - 7 = 18

$\Rightarrow$ a = 3

An algebraic expression which contains two unlike terms is called a binomial. For example, 8 + x, xy - 4 are binomials.

An algebraic expression which contains three unlike terms is called trinomial. For example, 8 + x + y, xy - 4x + y, etc.

So, the expression, $5x^2+5x+5$, is a trinomial as this expression contains three unlike terms, which are, $5x^2$, 5x and 5.
Hence the given statement is false.

In order to find the sum of $2mn+11xand22x+4mn$, we need to group the like terms first (we can add only the like terms).

$\Rightarrow (2mn+11x)+(22x+4mn)$
$=2mn+11x+22x+4mn$
$=(2mn+4mn)+(11x+22x)$
$=6mn+33x$

Hence, the sum is
$6mn+33x$.

Answer: 1 Mark
Example: 1 Mark
The product of a monomial and a binomial expression is a binomial.
E.g.  $a(a^2-b^2)=a^3-a{b}^2$ the expression has only two terms $a^3$ and $a{b}^2$.

$\to$ 6m + 10 − 10m
$\to$ (6m - 10m) + 10
$\to$ - 4m + 10 is the simplified form.

Coefficients and terms: 0.5 Mark each
Value of the expression: 1 Mark
Coefficients of $x^2$ and $x$ are 10 and - 5 respectively
Terms are $10x^2$, $-5x$ and $-6$
We have to find the value of the expression at $x=2$ is
$10\times 2\times 2-5\times 2-6$
= $40-10-6$
= $24$
Hence, the value of the expression at $x=2is24$