A metal alloy weighing 5kg and containing 22% iron melted and mixed with 12 kg of a different alloy which contains 90% iron. What percent of the resulting alloy is iron?

70%

Step-by-step explanation:

Given the weight of the first alloy as 5kg(22% iron) and the second as 12kg(90% iron:

#First, we find the weight in kgs of the iron in both alloys:

Hence, the weight of iron in the resulting alloy is 11.9kg.

#From the given info,the total mass of the alloy is 5+12=17kg

Therefore, the % of iron is calculated as :

Hence, 70% of the resulting alloy is iron.

the polynomial is a perfect square trinomial of the form a^2-2ab+b^2:

option a. true

step-by-step explanation:

9x^2-12x+4

comparing with the form a^2-2ab+b^2

1.) a^2=9x^2

solving for a: square root both sides of the equation:

sqrt(a^2)=sqrt(9x^2)

a=sqrt(9) sqrt(x^2)

a=3x

2.) b^2=4

solving for b: square root both sides of the equation:

sqrt(b^2)=sqrt(4)

b=2

to be a perfet square trinomial 2ab must be equal to 12x. let's check:

2ab = 2 (3x) (2)

2ab = 12x

correct