Hidden squares

= $15^{2}$ - $4^{2}$ =209

(15-4) x (15 + 4) = 11 x 19 = (10 x 19) + (1 x 19) = 190 + 19 = 209

(15-4)(15+4)=15^2-4^2=225-16=209

$( a + b ) \times ( a - b ) = a^{2} + ab - ab - b^{2} = a^{2} - b^{2}$

For this problem: $a = 15, b = 4$ .

$( 15 + 4 ) \times ( 15 - 4 ) = 15^{2} + 15 \times 4 - 15 \times 4 - 4^{2} = 225 + 60 - 60 -16 = 285 - 60 - 16 = 225 - 16 = \boxed{209}$ .

(15 - 4) x (15 + 4) = 15^2 - 4^2 = 209

15-4 = 11 15+4 = 19

11*19 = 209

deal with the brackets 15-4=11 15+4=19 then you take the two numbers and multiply them with each other 11 x 19 = 209

15^2-16^2=>225-16=>209

bodmas

Following the BODMAS - Brackets-Order-Division-Multiplication-Addition-Subtraction - We solve the Brackets first that is 15-4 and 15+ 4.. the answer to that is 11 and 19 respectively. Then what's left is multiplication between 11 and 19 which gives us the answer 209 11x19=209

15-4=11 AND 15+4=19 19*11=209

(15−4)×(15+4) =11×19 =209

11*19=209

(15-4) (15+4)= (11) (19)= 11*19=209

(A-B) (A+B) = A² - B²
And A=15 , B=4
=> Answer = 15²-4² => 225-16 => 209

simple (a+b)(a-b) formulae square of a - square of b

15-4=11 and 15+4=19 when you multiply any number with 11 you have to follow this steps 19 11= 209 9 comes from 19's 9 and then 19 make sum of numbers 9+1=10 and then 0 comes 1give to 19's one so 1+1 makes 2 now the anser comes 209 i give you another ex. 23 11=253 2 and 2+3 and 3

(15-4)x(15+4) = 15^2-4^2=209

(15-4)x(15+4) it is of the form (a+b)x(a-b) so we can write it as a^2 -b^2 therefore (15-4)x(15+4) = 15^2 - 4^2 = 225 -16 = 209 :)

(x+y) \times (x-y) = x^{2} - y^{2}

(15-4) * (15+4) = (11)*(19) = 209

I solved what was in the parenthesis first (15-4)= 11, then (15+4)= 19. Next you multiplied 11 x 19= 209

(15-4)x(15+4)= 11x19= 209 (220-11)

Since the numbers are in parentheses you do those problems first. So add 15 to 4 and you get 19. Then subtract 4 from 15 to get 11. Then multiply 11 and 19 and you get 209. That is your answer.

15-4 = 11 15+4 = 19 so (11)*(19)=209

The Easy Approach Is By Applying \boxed{ (a-b)(a+b) = a^{2}-b^{2}}