Answer:
49x² + 42x + 9
Step-by-step explanation:
Given
(7x + 3)²
= (7x + 3)(7x + 3)
Each term in the second factor is multiplied by each term in the first factor, that is
7x(7x + 3) + 3(7x + 3) ← distribute both parenthesis
= 49x² + 21x + 21x + 9 ← collect like terms
= 49x² + 42x + 9
The given expression is :
2xx+3-5(x-2)
We know that, 

Aleena expands 2xx+3-5(x-2) as 2x²+3-5x-10. She is mistaken because the sign before 10 should be +10 instead of -10. Hence, the correct expanded form is 2x²+3-5x+10. Hence, this is the required solution.
Answer:
(b)
Step-by-step explanation:
A suitable calculator or spreadsheet can find the matrix product for you. Here, the answer choices differ in their upper left term, so we can determine the correct choice by finding the value of that term. It is the dot product of the first row of B and the first column of A.
(5)(3) +(7)(3) +(3)(2) = 15 +21 +6 = 42
This matches choice B.

First we'll multiply the second equation by -2

Now let's add the new equation and the first one.

We found y's value. We'll plug it in one of the equations to find x's value.

Solution ;
(9, -6)