Question

if x=1;y=2 find the values of the following expressions
1). 4x-3y+5   2.) x² + y²    3) xy+3y-9

Answer 1

1).   4x-3y+5 = 4×1-3×2+5 = 4-6+5 = 3
$2). x^{2} + y^{2} = 1^{2} + 2^{2} = 1+4 =5$
$3). xy+3y-9 = 1*2+3*2-9=2+6-9=-1$

Answer 2

1) 4 * 1 - 3 * 2 + 5
= 4 - 6 + 5
= 3
2) 1² + 2²
= 5
3) 1 * 2 + 3 * 2 - 9
2 + 6 - 9
= -1