3. Given: a+b=12 and ab=9
Use (a + b)2 to find a² +bº. (Do not solve for a and b individually)

a²+b²=126

Step-by-step explanation:

(a+b)²=a²+b²+2ab

(12)²=a²+b²+2×9

144=a²+b²+18

a²+b²=144-18=126

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

hope it